Lithographic printing plate precursor, method of producing same, lithographic printing plate precursor laminate, and lithographic printing method

ABSTRACT

Provided are a lithographic printing plate precursor including: a hydrophilized aluminum support, and a water-soluble or water-dispersible negative type image recording layer provided on the aluminum support, in which an arithmetic average height Sa of a surface of an outermost layer on a side opposite to a side where the image recording layer is provided is in a range of 0.3 μm to 20 μm; a method of producing the lithographic printing plate precursor; a lithographic printing plate precursor laminate formed of the lithographic printing plate precursor; and a lithographic printing method.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of International Application No.PCT/JP2018/012606 filed on Mar. 27, 2018, which claims priority toJapanese Patent Application No. 2017-072052 filed on Mar. 31, 2017. Theentire contents of these applications are incorporated herein byreference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present disclosure relates to a lithographic printing plateprecursor, a method of producing the same, a lithographic printing plateprecursor laminate, and a lithographic printing method.

2. Description of the Related Art

A lithographic printing plate precursor is frequently stored andtransported as a laminate formed by laminating a plurality of sheetsthereof. In this laminate, interleaving paper is typically inserted intothe space between lithographic printing plate precursors for the purposeof preventing dislocation in stacking of lithographic printing plateprecursors, preventing adhesion between lithographic printing plateprecursors, and preventing scratches on a surface of a lithographicprinting plate precursor on an image recording layer side. However, in acase where interleaving paper is used, problems of cost increase, adisposal treatment, and the like may occur, and thus the interleavingpaper needs to be removed before an exposure step. Therefore, this mayalso result in risk of occurrence of a load on a plate-making step andoccurrence of interleaving paper peeling failure. Further, at the timeof removing the interleaving paper, it is necessary to giveconsideration so that the surface of the lithographic printing plateprecursor on the recording layer side is not damaged. Accordingly,development of a lithographic printing plate precursor that enableslamination without interleaving paper has been required.

Examples of lithographic printing plate precursors of the related artinclude those described in JP2008-249851A, JP2008-503365A,WO2014/202519A, and JP2007-093814A.

JP2008-249851A describes a lithographic printing plate precursor whichincludes a photosensitive layer containing (A) infrared absorbing agent,(B) borate compound, (C) radical polymerization initiator, (D)polymerizable compound having an unsaturated ethylenic double bond, (E)binder polymer, and (F) polymer fine particles on one surface of aroughened aluminum support and includes a back coat layer containing anorganic polymer compound on a photosensitive layer non-formed surface ofthe roughened aluminum support.

JP2008-503365A describes an image formable element which includes alithographic substrate; and a polymer binder containing (a) radicalpolymerizable component, (b) initiator system capable of generatingradicals sufficient to initiate a polymerization reaction when exposedto radiation for forming an image, (c) hydrophobic main chain, and bothof (i) constitutional unit that contains a pendant-cyano group directlybonded to the hydrophobic main chain and (ii) constitutional unit thatcontains a pendant group having a hydrophilic poly(alkylene oxide)segment.

WO2014/202519A describes a method of producing a lithographic printingplate precursor, including processes of preparing a support having afront surface and a rear surface as a web, coating the front surface ofthe support with an image recording layer, and adhering a discontinuousback layer onto the rear surface of the support according to an imagewhich has been defined in advance.

JP2007-093814A describes an infrared photosensitive lithographicprinting plate precursor including a recording layer, which contains awater-insoluble and alkali-soluble resin and an infrared absorbing agentand is capable of forming an image by irradiation with infrared rays, onone surface of a support; an organic polymer layer on a surface of thesupport on the opposite side of the surface where the recording layer isprovided; and a mat on at least one of the surface of the recordinglayer or the surface of the organic polymer layer.

SUMMARY OF THE INVENTION

A lithographic printing plate precursor (hereinafter, also simplyreferred to as a “precursor”) is typically used by laminating precursorsin a state of interposing interleaving paper between precursors for thepurpose of preventing dislocation in stacking precursors at the time ofproducing precursors, preventing adhesion between precursors, preventingmultiple precursors from being fed in a plate-making step of taking outprecursor from the stack one by one, preventing scratches at the time ofproducing and stacking precursors, performing transportation and in aseries of steps carried out at the time of user plate-making and beforeprinting. However, an aspect in which interleaving paper is not used(also referred to as “elimination of interleaving paper”) is employed insome cases for the purpose of preventing interleaving paper peelingfailure at the time of user plate-making, improving the plate-makingspeed, and reducing the cost.

In the lithographic printing plate precursor described in JP2008-249851Aor JP2008-503365A, in a case where an outermost layer on the surfacewhere the image recording layer is provided and an outermost layer onthe surface on the opposite side thereof are laminated by being directlybrought into contact with each other, the laminated precursors areadsorbed to each other in some cases.

WO2014/202519A and JP2007-093814A respectively describe a method ofpreparing a discontinuous shape on the rear surface of a precursor and amethod of forming an organic polymer layer on the rear surface of aprecursor and also describe methods of substituting the functions ofinterleaving paper by employing these methods.

These techniques are achieved using a lithographic printing plate(hereinafter, referred to as a “treated plate”) to be developed by analkali treatment liquid. However, there is a problem in which an imagerecording layer is damaged in a case of a lithographic printing plate(hereinafter, referred to as an “untreated plate”) to be developed(hereinafter, referred to as “on-press development”) on a printing pressbecause a protective layer is a thin film or is not present and theimage recording layer is designed to be brittle in order to impartpeeling properties and developability obtained by using tack power of anink.

Further, even in a case where development is performed using a developerand an automatic development treatment device, damage to the imagerecording layer may become a problem in a case where a protective layeris not present or a protective layer is a thin layer or depending on thecomposition of a protective layer.

Particularly in the untreated plate described in JP2008-249851A orJP2008-503365A, in a case where a discontinuous shape or a polymer layerdescribed in WO2014-202519A or JP2007-093814A is formed and laminated onthe rear surface of a precursor, the image recording layer(photosensitive layer) is damaged due to concentration of a pressure ona site of the image recording layer to be brought into contact withprojections of the discontinuous shape or the polymer layer.

In a case where a development treatment (an on-press developmenttreatment or a development treatment performed using a developer) isperformed using a printing plate precursor such as an untreated platehaving a damaged image recording layer, partial development delay occursand thus waste paper (the printed material generated until the desiredpaper quality is obtained) at the initial stage of printing isincreased.

In the present disclosure, partial development delay in the on-pressdevelopment is also referred to as “on-press development delay”.

An object of embodiments of the present invention in order to solve theproblems is to provide a lithographic printing plate precursor withexcellent development delay resistance and an excellent plate feedingproperty of taking out a precursor from a laminate; a method ofproducing the same; a lithographic printing plate precursor laminateformed of the lithographic printing plate precursor; and a lithographicprinting method.

The means for solving the above-described problems includes thefollowing aspects.

<1> A lithographic printing plate precursor comprising: a hydrophilizedaluminum support; and a water-soluble or water-dispersible negative typeimage recording layer on the aluminum support, in which an arithmeticaverage height Sa of a surface of an outermost layer on a side oppositeto a side where the image recording layer is provided is in a range of0.3 μm to 20 μm.

<2> The lithographic printing plate precursor according to <1>, in whichthe image recording layer contains an infrared absorbing agent, apolymerization initiator, a polymerizable compound, and a polymercompound having a particle shape.

<3> The lithographic printing plate precursor according to <2>, in whichthe polymer compound having a particle shape that is contained in theimage recording layer is obtained by reacting a polyvalent isocyanatecompound which is an adduct of a polyhydric phenol compound containingtwo or more hydroxy groups in a molecule and isophorone diisocyanatewith a compound containing an active hydrogen atom.

<4> The lithographic printing plate precursor according to <2>, in whichthe polymer compound having a particle shape that is contained in theimage recording layer has a hydrophobic main chain and both of (i)constitutional unit which contains a pendant-cyano group directly bondedto the hydrophobic main chain and (ii) constitutional unit whichcontains a pendant group having a hydrophilic polyalkylene oxidesegment.

<5> The lithographic printing plate precursor according to <1>, in whichthe image recording layer contains an infrared absorbing agent and athermoplastic polymer particle.

<6> The lithographic printing plate precursor according to any one of<1> to <5>, in which a Bekk smoothness of the surface of the outermostlayer on the side opposite to the side where the image recording layeris provided is 1000 seconds or less.

<7> The lithographic printing plate precursor according to any one of<1> to <6>, in which a resin layer which contains at least one kind ofparticles having an average particle diameter of 0.5 μm to 20 μm isprovided as the outermost layer on the side opposite to the side wherethe image recording layer is provided.

<8> The lithographic printing plate precursor according to <7>, in whicha film thickness of the resin layer is in a range of 0.6 μm to 2 μm.

<9> The lithographic printing plate precursor according to <8> whichsatisfies Expression (A).

0.2≤(the film thickness of the resin layer/the average particle diameterof the particles contained in the resin layer)≤0.5  Expression (A)

<10> The lithographic printing plate precursor according to any one of<7> to <9>, in which a density of the particles is in a range of 500pcs/m² to 500000 pcs/m².

<11> The lithographic printing plate precursor according to any one of<7> to <10>, in which the resin layer contains a binder, and adifference in solubility parameter between the particles and the binderis 4 MPa^(1/2) or less.

<12> The lithographic printing plate precursor according to <11>, inwhich the particles and the binder each contain at least one selectedfrom the group consisting of polyurethane, an acrylic resin,polystyrene, and polyethylene.

<13> The lithographic printing plate precursor according to any one of<7> to <12>, in which a 10% hardness of the particles is 80 MPa or less.

<14> The lithographic printing plate precursor according to any one of<1> to <6>, in which a plurality of protrusions are provided on thesurface of the outermost layer on the side opposite to the side wherethe image recording layer is provided.

<15> The lithographic printing plate precursor according to any one of<1> to <6>, in which a resin layer is provided as the outermost layer onthe side opposite to the side where the image recording layer isprovided, and a plurality of protrusions containing a polymer compoundare provided on the resin layer.

<16> The lithographic printing plate precursor according to <14> or<15>, in which an average height of the protrusions is in a range of 0.5μm to 20 μm.

<17> The lithographic printing plate precursor according to any one of<14> to <16>, in which a density of the protrusions is in a range of 500pcs/m² to 500000 pcs/m².

<18> The lithographic printing plate precursor according to any one of<1> to <17>, in which an arithmetic average height Sa of a surface of anoutermost layer on the side where the image recording layer is providedis smaller than the arithmetic average height Sa of the surface of theoutermost layer on the side opposite to the side where the imagerecording layer is provided.

<19> The lithographic printing plate precursor according to any one of<1> to <19>, which satisfies Expression (1) and Expression (2) in a casewhere a Bekk smoothness of a surface of an outermost layer on the sidewhere the image recording layer is provided is set as a seconds and aBekk smoothness of the surface of the outermost layer on the sideopposite to the side where the image recording layer is provided is setas b seconds.

a≤1000  (1)

1/a+1/b≥0.002  (2)

<20> The lithographic printing plate precursor according to any one of<1> to <19>, in which the aluminum support includes an aluminum plateand an aluminum anodized film disposed on the aluminum plate, theanodized film is positioned closer to the image recording layer sidethan to the aluminum plate, the anodized film has micropores extendingin a depth direction from the surface of the image recording layer side,and the average diameter of the micropores in the surface of theanodized film is in a range of 7 nm to 150 nm.

<21> The lithographic printing plate precursor according to <20>, inwhich the average diameter of the micropores in the surface of theanodized film is in a range of 10 nm to 100 nm.

<22> The lithographic printing plate precursor according to <20> or<21>, in which the micropores are formed of large-diameter poresextending to a position at a depth of 10 nm to 1000 nm from the surfaceof the anodized film and small-diameter pores communicating with abottom of the large-diameter pores and extending to a position at adepth of 20 nm to 2000 nm from a communication position, the averagediameter of the large-diameter pores in the surface of the anodized filmis in a range of 15 nm to 150 nm, and the average diameter of thesmall-diameter pores in the communication position is 13 nm or less.

<23> A lithographic printing plate precursor laminate which is obtainedby laminating a plurality of the lithographic printing plate precursorsaccording to any one of <1> to <22>, in which an outermost layer on theside where the image recording layer is provided and the outermost layeron the side opposite to the side where the image recording layer isprovided are laminated by being directly brought into contact with eachother.

<24> A method of producing the lithographic printing plate precursoraccording to any one of <1> to <22>, comprising: a step of forming theimage recording layer on the aluminum support after one or more daysfrom an anodization treatment performed thereon.

<25> A lithographic printing method comprising: a step of image-exposingthe lithographic printing plate precursor according to any one of <1> to<22>; a step of supplying at least any of printing ink or dampeningwater and removing an unexposed portion of an image recording layer on aprinting press to prepare a lithographic printing plate; and a step ofperforming printing using the obtained lithographic printing plate.

<26> A lithographic printing method comprising: a step of image-exposingthe lithographic printing plate precursor according to any one of <1> to<22>; a development step of supplying a developer having a pH of 2 to 14and removing an unexposed portion; and a step of performing printingusing the obtained lithographic printing plate.

According to the embodiment of the present invention, it is possible toprovide a lithographic printing plate precursor with excellentdevelopment delay resistance and an excellent plate feeding property oftaking out a precursor from a laminate; a method of producing the same;a lithographic printing plate precursor laminate formed of thelithographic printing plate precursor; and a lithographic printingmethod.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view illustrating an embodiment ofan aluminum support.

FIG. 2 is a schematic cross-sectional view illustrating anotherembodiment of an aluminum support.

FIG. 3 is a graph showing an alternating waveform current waveformdiagram used for an electrochemical roughening treatment according to amethod of producing an aluminum support.

FIG. 4 is a side view illustrating an example of a radial type cell inthe electrochemical roughening treatment carried out using thealternating current according to the method of producing an aluminumsupport.

FIG. 5 is a side view illustrating an example of a radial type cell inthe electrochemical roughening treatment carried out using thealternating current according to the method of producing an aluminumsupport having an anodized film.

FIG. 6 is a side view illustrating the concept of a brush graining stepused for a mechanical roughening treatment carried out according to themethod of producing an aluminum support having an anodized film.

FIG. 7 is a configuration view illustrating the outline of an automaticdevelopment device used in the examples of the present application.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the contents of the present disclosure will be described indetail. The description of constituent elements below is made based onrepresentative embodiments of the present disclosure in some cases, butthe present disclosure is not limited to such embodiments.

Further, in the present specification, the numerical ranges shown using“to” indicate ranges including the numerical values described before andafter “to” as the lower limits and the upper limits.

In the present specification, in a case where substitution orunsubstitution is not noted in regard to the notation of a “group”(atomic group) in the present specification, the “group” includes notonly a group that does not have a substituent but also a group having asubstituent. For example, the concept of an “alkyl group” includes notonly an alkyl group that does not have a substituent (unsubstitutedalkyl group) but also an alkyl group having a substituent (substitutedalkyl group).

In the present specification, the concept of “(meth)acryl” includes bothof acryl and methacryl, and the concept of “(meth)acryloyl” includesboth of acryloyl and methacryloyl.

Further, the term “step” in the present specification indicates not onlyan independent step but also a step which cannot be clearlydistinguished from other steps as long as the intended purpose of thestep is achieved. Further, in the present disclosure, “% by mass” hasthe same definition as that for “% by weight”, and “part by mass” hasthe same definition as that for “part by weight”.

Further, in the present disclosure, a combination of two or morepreferred aspects is a more preferred aspect.

Further, the weight-average molecular weight (Mw) and the number averagemolecular weight (Mn) in the present disclosure are molecular weights interms of polystyrene used as a standard substance, which are detected byusing a solvent tetrahydrofuran (THF), a differential refractometer, anda gel permeation chromatography (GPC) analyzer using TSKgel GMHxL,TSKgel G4000HxL, and TSKgel G2000HxL (all trade names, manufactured byTosoh Corporation) as columns, unless otherwise specified.

In the present specification, the term “lithographic printing plateprecursor” includes not only a lithographic printing plate precursor butalso a key plate precursor. Further, the term “lithographic printingplate” includes not only a lithographic printing plate prepared byperforming operations such as exposure and development on a lithographicprinting plate precursor as necessary but also a key plate. In a case ofa key plate precursor, the operations of exposure, development, and thelike are not necessarily required. Further, a key plate is alithographic printing plate precursor for attachment to a plate cylinderthat is not used in a case where printing is performed on a part of apaper surface with one or two colors in color newspaper printing.

Hereinafter, the present disclosure will be described in detail.

(Lithographic Printing Plate Precursor)

A lithographic printing plate precursor according to the presentdisclosure includes a hydrophilized aluminum support (simply referred toas a “support”); and a water-soluble or water-dispersible negative typeimage recording layer (simply referred to as an “image recording layer”)provided on the aluminum support, in which an arithmetic average heightSa of a surface of an outermost layer on a side opposite to a side wherethe image recording layer is provided is in a range of 0.3 μm to 20 μm.

In other words, the lithographic printing plate precursor according tothe present disclosure includes a support and an image recording layerformed on the support, and the arithmetic average height Sa of thesurface of the outermost layer on a side opposite to a side where theimage recording layer is provided is in a range of 0.3 μm to 20 μm.

In the present disclosure, the side of the lithographic printing plateprecursor opposite to a side where the image recording layer is providedindicates a side opposite to a side where the image recording layer isprovided using the support as a reference.

Hereinafter, in the present disclosure, the surface of the outmost layeron a side of the lithographic printing plate precursor where the imagerecording layer is provided is also referred to as a “front surface” andthe surface of the outermost layer on a side opposite to a side wherethe image recording layer is provided is also referred to as a “rearsurface”.

As the result of intensive examination conducted by the presentinventors, it was found that a lithographic printing plate withexcellent development delay resistance and an excellent plate feedingproperty of taking out a precursor from a laminate can be provided in acase where the lithographic printing plate precursor according to thepresent disclosure has the above-described configuration.

The mechanism in which the above-described excellent effects areobtained is not clear, but can be assumed as follows.

The present inventors found that there is a problem in that partialdevelopment delay occurs and thus waste paper (the printed materialgenerated until the desired paper quality is obtained) at the initialstage of printing is increased in a case where developable lithographicprinting plate precursors are used and the precursors are laminated bysimply imparting unevenness to each rear surface to eliminateinterleaving paper.

The reason for this is considered that a pressure is partiallyconcentrated on the front surface and this results in damage to theimage recording layer in this portion.

As the result of intensive examination conducted by the presentinventors, it was found that the above-described development delay canbe eliminated or reduced so that the development delay resistancebecomes excellent by setting the arithmetic average height Sa of therear surface to be in a range of 0.3 μm to 20 μm.

Further, particularly in a case where the lithographic printing plateprecursor according to the present disclosure is an on-press developmenttype lithographic printing plate precursor, the lithographic printingplate precursor has excellent on-press development delay resistance andalso has development delay resistance in the development using adeveloper.

It is considered that the development delay resistance is excellent asdescribed above because large projections are unlikely to be formed onthe rear surface, concentration of the pressure on a part of the frontsurface is suppressed, and damage to the image recording layer isreduced by setting the arithmetic average height Sa of the rear surfaceto be in a range of 0.3 μm to 20 μm.

Further, the present inventors found that feeding of multiple precursorsis suppressed due to the unevenness in the surface of the outermostlayer and the plate feeding property is excellent in a case wherelithographic printing plate precursors are taken out from thelithographic printing plate precursor laminate one by one, by settingthe arithmetic average height Sa of the rear surface to be in a range of0.3 μm to 20 μm.

This is also considered to be due to any or both of a decrease incontact area from a microscopic viewpoint of the rear surface and thefront surface and the air easily passing through at the time of peeling(also referred to as an “air release property”) in a case whereprecursors are laminated using interleaving paper, by setting thearithmetic average height Sa of the rear surface to be in a range of 0.3μm to 20 μm.

The lithographic printing plate precursor in the present disclosureincludes a support and a water-soluble or water-dispersible negativetype image recording layer on the support.

The lithographic printing plate precursor according to the presentdisclosure may be a lithographic printing plate precursor used foron-press development or a lithographic printing plate precursor used fordevelopment carried out with a developer.

Further, the lithographic printing plate precursor according to thepresent disclosure may include an undercoat layer between the supportand the image recording layer, may include a protective layer on theimage recording layer, or may include a resin layer (back coat layer) ona side of the support opposite to a side where the image recording layeris provided.

In the lithographic printing plate precursor according to the presentdisclosure, the arithmetic average height Sa of the surface of theoutermost layer on a side opposite to a side where the image recordinglayer is provided is in a range of 0.3 μm to 20 μm.

The surface of the outermost layer is a surface of the resin layer in acase where the lithographic printing plate precursor has theabove-described resin layer and is a surface of the support in a casewhere the lithographic printing plate does not have a layer on thesupport.

For example, in a case where protrusions described below are formed, theresin layer of the lithographic printing plate precursor according tothe present disclosure is an outermost layer and a plurality ofprotrusions containing a polymer compound may be provided on the resinlayer. Further, the support of the lithographic printing plate precursoraccording to the present disclosure is an outermost layer and aplurality of protrusions containing a polymer compound may be providedon the support.

<Arithmetic Average Height Sa>

[Rear Surface]

In the lithographic printing plate precursor according to the presentdisclosure, the arithmetic average height of the surface (rear surface)of the outermost layer on a side opposite to a side where the imagerecording layer is provided is preferably 0.5 μm or greater and lessthan 20 μm, more preferably 0.5 μm or greater and less than 15 μm, andstill more preferably 0.5 μm to 10 μm from the viewpoints of thedevelopment delay resistance, the plate feeding property of taking out aprecursor from a laminate, suppression of falling of particles, scratchresistance, and ease of peeling at the time of lamination without usinginterleaving paper.

In the present disclosure, the arithmetic average height Sa is measuredin conformity with the measuring method described in ISO 25178.Specifically, the arithmetic average height Sa is obtained by selectingthree or more sites from the same sample, performing the measurementthereon using MICROMAP MM3200-M100 (manufactured by Mitsubishi ChemicalSystems, Inc.), and averaging the obtained values. In regard to themeasurement region, a region having a size of 1 cm×1 cm which has beenrandomly selected from a surface of the sample is measured.

[Front Surface]

In the lithographic printing plate precursor according to the presentdisclosure, from the viewpoints of the development delay resistance, theplate feeding property of taking out a precursor from a laminate,suppression of falling of particles, scratch resistance, and ease ofpeeling at the time of lamination without using interleaving paper, thearithmetic average height Sa of the front surface is preferably in arange of 0.3 μm to 20 μm, more preferably 0.5 μm or greater and lessthan 10 μm, still more preferably 0.5 μm or greater and less than 7 μm,and particularly preferably 0.5 μm or greater and less than 3 μm.

Further, it is preferable that the arithmetic average height Sa of thefront surface is smaller than the arithmetic average height Sa of therear surface.

As the front surface, a surface of the image recording layer or asurface of a protective layer in a case where a protective layer isprovided on the image recording layer is exemplified.

[Total Value]

In the lithographic printing plate precursor according to the presentdisclosure, from the viewpoints of the development delay resistance, theplate feeding property of taking out a precursor from a laminate,suppression of falling of particles, scratch resistance, and ease ofpeeling at the time of lamination without using interleaving paper, thetotal value of the arithmetic average height Sa of the surface of theoutermost layer on the surface where the image recording layer isprovided and the arithmetic average height Sa of the surface of theoutermost layer on a side opposite to a side where the image recordinglayer is provided is preferably greater than of 0.3 μm and 20 μm orless, more preferably greater than 0.5 μm and less than 15 μm, andparticularly preferably greater than 0.5 μm and less than 10 μm.

<Bekk Smoothness>

[Rear Surface]

In the lithographic printing plate precursor according to the presentdisclosure, from the viewpoints of the plate feeding property of takingout a precursor from a laminate and ease of peeling at the time oflamination without using interleaving paper, a Bekk smoothness b of therear surface is preferably 1000 seconds or shorter, more preferably 500seconds or shorter, and still more preferably 300 seconds or shorter.

[Front Surface]

Further, in the lithographic printing plate precursor according to thepresent disclosure, from the viewpoints of the plate feeding property oftaking out a precursor from a laminate and ease of peeling at the timeof lamination without using interleaving paper, a Bekk smoothness a ofthe front surface is preferably 1000 seconds or shorter, more preferably300 seconds or shorter, and still more preferably 100 seconds orshorter.

Further, in the lithographic printing plate precursor according to thepresent disclosure, from the viewpoints of the development delayresistance, the plate feeding property of taking out a precursor from alaminate, suppression of falling of particles, scratch resistance, andease of peeling at the time of lamination without using interleavingpaper, in a case where the Bekk smoothness of the surface (frontsurface) of the outermost layer on the surface where the image recordinglayer is provided is set as a seconds and the Bekk smoothness of thesurface (rear surface) of the outermost layer on the surface opposite tothe surface where the image recording layer is provided is set as bseconds, it is preferable that at least one of Expression (1) orExpression (2) is satisfied and more preferable that both of Expression(1) and Expression (2) are satisfied.

a≤1000  (1)

1/a+1/b≥0.002  (2)

Further, from the viewpoints of the development delay resistance, theplate feeding property of taking out a precursor from a laminate,suppression of falling of particles, scratch resistance, and ease ofpeeling at the time of lamination without using interleaving paper, thevalue of 1/a+1/b is more preferably 0.004 s⁻¹ and still more preferably0.01 s⁻¹.

<Preferred Aspect of Rear Surface>

In the lithographic printing plate precursor according to the presentdisclosure, an aspect for achieving the arithmetic average height Sa ofthe rear surface is not particularly limited, and preferred examplesthereof include aspects in (Aspect A1) and (Aspect A2) described below.

(Aspect A1): The lithographic printing plate precursor includes a resinlayer containing at least one kind of particles having an averageparticle diameter of 0.5 μm to 20 μm as the outermost layer on a sideopposite to a side where the image recording layer is provided.

(Aspect A2): The lithographic printing plate precursor has a pluralityof protrusion containing a polymer compound on the surface (rearsurface) of the outermost layer on a side opposite to a side where theimage recording layer is provided.

Preferred examples of the method for obtaining the lithographic printingplate precursor according to the (Aspect A1) include a method of addingparticles to a composition for forming a resin layer.

Preferred examples of the method for obtaining the lithographic printingplate precursor according to the (Aspect A2) include a method of coatingthe surface of the outermost layer with a composition containing atleast one selected from the group consisting of particles and a polymercompound to form protrusions.

In the (Aspect A2), it is preferable that the lithographic printingplate precursor includes a resin layer as the outermost layer on a sideof the support opposite to a side where the image recording layer isprovided and has the plurality of protrusions on the resin layer.

[Resin Layer]

The film thickness of the resin layer is preferably in a range of 0.5 μmto 3 μm, more preferably in a range of 0.6 μm to 2 μm, and still morepreferably in a range of 0.8 μm to 1.5 μm.

It is preferable that the resin layer in the (Aspect A1) described abovecontains particles and a binder.

It is preferable that the resin layer in the (Aspect A2) described abovecontains a binder.

In the resin layer in the (Aspect A1), from the viewpoints of thedevelopment delay resistance, the plate feeding property of taking out aprecursor from a laminate, suppression of falling of particles, scratchresistance, and ease of peeling at the time of lamination without usinginterleaving paper, the density of particles is preferably in a range of500 pcs/m² to 500000 pcs/m², more preferably 1000 pcs/m² to 100000pcs/m², and still more preferably 5000 pcs/m² to 50000 pcs/m².

In the resin layer in the (Aspect A2), from the viewpoints of thedevelopment delay resistance, the plate feeding property of taking out aprecursor from a laminate, suppression of falling of particles, scratchresistance, and ease of peeling at the time of lamination without usinginterleaving paper, the density of protrusions is preferably in a rangeof 500 pcs/m² to 500000 pcs/m², more preferably 1000 pcs/m² to 100000pcs/m², and still more preferably 5000 pcs/m² to 50000 pcs/m².

—Particles—

The particles contained in the resin layer according to the (Aspect A1)and the particles used for achieving the (Aspect A2) are notparticularly limited, but at least one kind of particles selected fromthe group consisting of organic resin particles and inorganic particlesare preferable from the viewpoint of the development delay resistance.

<<Organic Resin Particles>>

Preferred examples of the organic resin particles include polyolefinssuch as poly(meth)acrylic acid esters, polystyrene and derivativesthereof, polyamides, polyimides, low-density polyethylene, high-densitypolyethylene, and polypropylene; particles formed of synthetic resinssuch as polyurethanes, polyureas, and polyesters; and particles formedof natural polymers such as chitin, chitosan, cellulose, crosslinkedstarch, and crosslinked cellulose.

Among these, synthesis resin particles have advantages that the particlesize can be easily controlled and desired surface characteristics can beeasily controlled by surface modification.

As a method of producing such organic resin particles, atomization canalso be made using a crushing method in a case of a relatively hardresin such as polymethyl methacrylate (PMMA), but a method ofsynthesizing particles using an emulsion suspension polymerizationmethod is preferably employed from the viewpoints of ease of controllingthe particle diameter and the precision.

The method of producing organic resin particles is described in detailin “Ultrafine Particle as Materials” edited by Materials Science Societyof Japan, published by SHOKABO Co., Ltd., 1993 and “Manufacturing &Application of Microspheres & Powders” supervised by Haruma Kawaguchi,published by CMC Publishing, 2005.

Examples of commercially available products of the organic resinparticles include crosslinked acrylic resins MX-40T, MX-80H3wT, MX-150,MX-180TA, MX-300, MX-500, MX-1000, MX-1500H, MR-2HG, MR-7HG, MR-10HG,MR-3GSN, MR-5GSN, MR-7G, MR-10G, MR-5C, and MR-7GC, and styrylresin-based SX-350H and SX-500H (manufactured by Soken Chemical &Engineering Co., Ltd.), Acrylic resins MBX-5, MBX-8, MBX-12, MBX-15,MBX-20, MB20X-5, MB30X-5, MB30X-8, MB30X-20, SBX-6, SBX-8, SBX-12, andSBX-17 (manufactured by Sekisui Plastics Co., Ltd.), polyolefin resinsand CHEMIPEARL W100, W200, W300, W308, W310, W400, W401, W405, W410,W500, WF640, W700, W800, W900, W950, and WP100 (manufactured by MitsuiChemicals, Inc.).

<<Inorganic Particles>>

Examples of the inorganic particles include silica, alumina, zirconia,titania, carbon black, graphite, BaSO₄, ZnS, MgCO₃, CaCO₃, ZnO, CaO,WS₂, MoS₂, MgO, SnO₂, α-Fe₂O₃, α-FeOOH, SiC, CeO₂, BN, SiN, MoC, BC, WC,titanium carbide, corundum, artificial diamond, petroleum stone, garnet,silica stone, tripolite, diatomaceous earth, and dolomite.

As the above-described particles, a particle having a hydrophilicsurface is preferable. Examples of the particle having a hydrophilicsurface include an organic resin particle having a hydrophilic surfaceand an inorganic particle having a hydrophilic surface.

As the organic resin particle having a hydrophilic surface, an organicresin particle covered with at least one inorganic compound selectedfrom the group consisting of silica, alumina, titania, and zirconia ispreferable and an organic resin particle covered with silica isparticularly preferable.

It is preferable that an organic resin constituting an organic resinparticle having a hydrophilic surface is at least one resin selectedfrom the group consisting of a polyacrylic resin, a polyurethane-basedresin, a polystyrene-based resin, a polyester-based resin, anepoxy-based resin, a phenolic resin, and a melamine resin.

Hereinafter, the organic resin particle having a hydrophilic surfacewill be described in detail using an organic resin particle covered withsilica (hereinafter, also referred to as a “silica-coated organic resinparticle”) as an example, and the organic resin particle having ahydrophilic surface in the present disclosure is not limited thereto.

The silica-coated organic resin particle is a particle obtained bycoating the surface of the particle formed of an organic resin withsilica. It is preferable that the organic resin particle constitutingthe core is not softened or does not become sticky due to the moisturein the air or the temperature thereof.

Examples of the organic resin constituting the organic resin particle inthe silica-coated organic resin particles include a polyacrylic resin, apolyurethane-based resin, a polystyrene-based resin, a polyester-basedresin, an epoxy-based resin, a phenol resin, and a melamine resin.

As a material forming the silica layer covering the surface of thesilica-coated organic resin particle, a compound containing analkoxysilyl group such as a condensate of an alkoxysiloxane-basedcompound, particularly, a siloxane-based material, and specifically,silica particles such as silica sol, colloidal silica, and silicananoparticles are preferably exemplified.

The configuration of the silica-coated organic resin particle may be aconfiguration in which a silica particle adheres to the surface of anorganic resin particle as a solid component or a configuration in whicha siloxane-based compound layer is formed on the surface of an organicresin particle by performing a condensation reaction on analkoxysiloxane-based compound.

Silica does not necessarily cover the entire surface of the organicresin particle, and it is preferable that the surface thereof is coveredwith at least 0.5% by mass or greater of silica at least with respect tothe total mass of the organic resin particles. In other words, in a casewhere silica is present on at least a part of the surface of the organicresin particle, improvement in affinity for a coexisting water-solublepolymer such as polyvinyl alcohol (PVA) is achieved, falling off of theparticle is suppressed even in a case where external stress is appliedthereto, and excellent scratch resistance and ease of peeling at thetime of lamination without using interleaving paper can be maintained.Accordingly, the expression “covered with silica” in the presentdisclosure includes a state in which silica is present on at least apart of the surface of the organic resin particle as described above.

The state of the surface being covered with silica can be confirmed bymorphological observation using a scanning electron microscope (SEM) orthe like. Further, the coating amount of silica can be confirmed bydetecting Si atoms through elemental analysis such as fluorescent X-rayanalysis and calculating the amount of silica present therein.

A method of producing silica-coated organic resin particles is notparticularly limited, and examples thereof include a method of forming asilica surface coating layer simultaneously with formation of organicresin particles by allowing silica particles or a silica precursorcompound to coexist with a monomer component which becomes the rawmaterial of the organic resin particles; and a method of forming organicresin particles, physically adhering silica particles to each surface ofthe organic resin particles, and fixing the silica particles thereto.

Hereinafter, an example of the method of producing silica-coated organicresin particles will be described. First, silica and a raw materialresin (more specifically, a raw material resin such as a monomer capableof suspension polymerization, a pre-polymer capable of suspensioncross-linking, or a resin liquid, constituting the above-describedorganic resin) are added to water containing a suspension stabilizerappropriately selected from a water-soluble polymer such as polyvinylalcohol, methyl cellulose, or polyacrylic acid and an inorganicsuspending agent such as calcium phosphate or calcium carbonate, andstirred and mixed with the water to prepare a suspension in which silicaand a raw material resin are dispersed. At this time, a suspensionhaving a target particle diameter can be formed by adjusting the type,the concentration, and the stirring rotation speed of the suspensionstabilizer. Next, the suspension is heated to start the reaction, andresin particles are generated by performing suspension polymerization orsuspension cross-linking on the resin raw material. At this time, thecoexisting silica is fixed to the resin particle cured by thepolymerization or the cross-linking reaction, particularly, the vicinityof the surface of the resin particle due to the physical propertiesthereof. Thereafter, the suspension is subjected to solid-liquidseparation, the suspension stabilizer adhering to the particles isremoved by washing, and the particles are dried. In this manner,silica-coated organic resin particles to which silica is fixed and whichhave a desired particle diameter and a substantially spherical shape canbe obtained.

As described above, silica-coated organic resin particles having adesired particle diameter can be obtained by controlling the conditionsduring the suspension polymerization or the suspension cross-linking orsilica-coated organic resin particles are generated without strictlycontrolling the conditions and then silica-coated organic particleshaving a desired size can be obtained by a mesh filtration method or thelike.

In regard to the amount of the raw material to be added to the mixtureduring the production of the silica-coated organic particles accordingto the above-described method, in a case where the total amount of theraw material resin and the silica is 100 parts by mass, an aspect inwhich 0.1 parts by mass to 20 parts by mass of the suspension stabilizeris firstly added to 200 parts by mass to 800 parts by mass of waterserving as a dispersion medium, and sufficiently dissolved or dispersedtherein, 100 parts by mass of a mixture of the raw material resin andthe silica is put into the solution, the solution is stirred while thestirring speed is adjusted such that the dispersed particles have apredetermined particle size, and the solution temperature is increasedto 30° C. to 90° C. after the adjustment of the particle size to cause areaction for 1 hour to 8 hours is preferably exemplified.

The above-described method is merely an example of the method ofproducing silica-coated organic resin particles and silica-coatedorganic resin particles obtained by the methods specifically describedin JP2002-327036A, JP2002-173410A, JP2004-307837A, JP2006-038246A, andthe like can be also suitably used in the present disclosure.

Further, the silica-coated organic resin particles are also available ascommercially available products, and specific examples ofsilica-melamine composite particles include OPTBEADS 2000M, OPTBEADS3500M, OPTBEADS 6500M, OPTBEADS 10500M, OPTBEADS 3500S, and OPTBEADS6500S (all manufactured by Nissan Chemical Industries, Ltd.). Specificexamples of silica-acrylic composite particles include ART PEARL G-200transparent, ART PEARL G-400 transparent, ART PEARL G-800 transparent,ART PEARL GR-400 transparent, ART PEARL GR-600 transparent, ART PEARLGR-800 transparent, and ART PEARL J-7P (all manufactured by NegamiChemical Industrial Co., Ltd.). Specific examples of silica-urethanecomposite particles include ART PEARL C-400 transparent, C-800transparent, P-800T, U-600T, U-800T, CF-600T, CF800T (all manufacturedby Negami Chemical Industrial Co., Ltd.) and DYNAMIC BEADS CN5070D andDANPLACOAT THU (both manufactured by Dainichiseika Color & ChemicalsMfg. Co., Ltd.).

Hereinbefore, the organic resin particles used in the present disclosurehave been described using the silica-coated organic resin particles asan example, but the same applies to organic resin particles covered withalumina, titania, or zirconia by using alumina, titania, or zirconia inplace of silica.

<<Shape>>

As the shape of particles, a perfectly spherical shape is preferable,and a flat plate shape or a so-called spindle shape in which aprojection view is in an elliptical shape may be employed.

From the viewpoint of the development delay resistance, the averageparticle diameter of particles used for forming unevenness on the rearsurface is preferably 0.1 μm or greater, more preferably 0.3 μm orgreater, still more preferably 0.5 μm or greater, and particularlypreferably 0.7 μm or greater. Further, from the viewpoint of thedevelopment delay resistance, the average particle diameter thereof ispreferably 20 μm or less, more preferably 10 μm or less, and still morepreferably 7 μm or less.

In addition, from the viewpoints of the development delay resistance,the plate feeding property of taking out a precursor from a laminate,suppression of falling of particles, scratch resistance, and ease ofpeeling at the time of lamination without using interleaving paper, itis preferable that the resin layer according to the (Aspect A1)satisfies Expression (A).

0.2≤(the film thickness of the resin layer/the average particle diameterof the particles contained in the resin layer)≤0.5  Expression (A)

The value of (the film thickness of the resin layer/the average particlediameter of the particles contained in the resin layer) is preferably0.2 or greater, more preferably 0.22 or greater, and still morepreferably 0.25 or greater. Further, the value thereof is preferably 0.5or less, more preferably 0.45 or less, and still more preferably 0.4 orless.

The value represented by (the film thickness of the resin layer/theaverage particle diameter of the particles contained in the resin layer)is also referred to as a particle embedment rate.

From the viewpoint of the development delay resistance, the averageparticle diameter of the particles used for forming unevenness on thefront surface described below is preferably in a range of 0.1 μm to 20μm, more preferably in a range of 0.3 μm to 10 μm, still more preferablyin a range of 0.5 μm to 7 μm, and particularly preferably in a range of0.5 μm to 5 μm.

The average particle diameter of the particles in the present disclosureindicates the volume average particle diameter, and the volume averageparticle diameter can be measured using a laser diffraction andscattering type particle size distribution meter. Examples of themeasuring device include a particle size distribution measuring device“Microtrac MT-3300II” (manufactured by Nikkiso Co., Ltd.).

Further, in the present disclosure, the average particle diameter ofother particles is set to be measured according to the above-describedmeasurement method unless otherwise specified.

—Hardness—

The 10% hardness of the particles is preferably 80 MPa or less, morepreferably 50 MPa or less, and still more preferably 40 MPa or less.Further, the 10% hardness thereof is preferably 1 MPa or greater andmore preferably 10 MPa or greater.

The 10% hardness of the particles indicates the hardness obtained in acase where 10% of the particles are pushed in and is measured using amicro compression tester MCT Series (manufactured by ShimadzuCorporation). Specifically, the particles are interposed until thediameter thereof reaches 90% of the length and the pressure at that timeis measured.

<<Addition Amount>>

[Rear Surface]

In a case where the particles are added to a composition for forming aresin layer in order to form unevenness on the rear surface, the amountof the particles to be added to the outermost layer is adjusted suchthat the amount of the particles, which are present on the resin layer,is preferably in a range of 500 pcs/m² to 500000 pcs/m², more preferablyin a range of 1000 pcs/m² to 100000 pcs/m², and still more preferably ina range of 5000 pcs/m² to 50000 pcs/m². In a case where the amount ofthe particles to be added is in the above-described range, thearithmetic average height Sa is easily adjusted to be in theabove-described range and desorption of particles is prevented so thatthe failure is not caused.

[Front Surface]

According to the following aspect, in a case where the particles areadded to a composition for forming an outermost layer in order to formunevenness on the front surface, the mass of the particles to be addedis preferably in a range of 0.5% by mass to 50% by mass, more preferablyin a range of 1.0% by mass to 20% by mass, and still more preferably ina range of 2.5% by mass to 10% by mass with respect to 100% by mass ofthe total mass of the outermost layer. In a case where the mass of theparticles to be added is in the above-described range, the plate feedingproperty of taking out a precursor from a laminate, suppression offalling of particles, scratch resistance, and ease of peeling at thetime of lamination without using interleaving paper become excellent.

From the viewpoints of the plate feeding property of taking out aprecursor from a laminate, suppression of falling of particles, scratchresistance, and ease of peeling at the time of lamination without usinginterleaving paper, the image recording layer contains at least one kindof particles having an average particle diameter of 0.5 μm to 20 μm andit is preferable that the image recording layer contains two or morekinds of particles having different average particle diameters.

It is preferable that the particles having an average particle diameterof 0.5 μm to 20 μm are particles for forming the unevenness, andexamples of other particles include a polymer compound having a particleshape and thermoplastic polymer particles described below.

In the present disclosure, “the image recording layer contains two ormore kinds of particles having different average particle diameters” isconfirmed by checking whether two or more peaks are present in theparticle size distribution. The particle size distribution is measuredin the same manner as that for the average particle diameter of theparticles or acquired by imaging an electron micrograph of particles,measuring the total number of 5,000 particle diameters of particles onthe photograph, dividing the interval from the maximum value of theobtained measured value of the particle diameter to 0 into thelogarithmic scale of 50, and plotting the appearance frequency of eachparticle diameter. Further, the particle diameter of a sphericalparticle having the same particle area as the particle area on thephotograph was set to the particle diameter, as non-spherical particles.

Further, the two or more peaks described above are preferably peaksseparated from each other by 10 nm or longer, and more preferably peaksseparated from each other by 100 nm or longer.

—Binder—

It is preferable that the binder according to the (Aspect A1) containsat least one selected from the group consisting of a novolak resin suchas a phenol formaldehyde resin, an m-cresol formaldehyde resin, ap-cresol formaldehyde resin, an m-/p-mixed cresol formaldehyde resin, ora phenol/cresol (any of m-, p-, and m-/p-mixed)-mixed formaldehyderesin, a resol resin, pyrogallol, an acetone resin, an epoxy resin, asaturated copolymer polyester resin, a phenoxy resin, a polyvinyl acetalresin, a vinylidene chloride copolymer resin, polybutene, polybutadiene,polyamide, an unsaturated copolymer polyester resin, polyurethane,polyurea, polyimide, polysiloxane, polycarbonate, chlorinatedpolyethylene, an aldehyde condensation resin of alkyl phenol, polyvinylchloride, polyvinylidene chloride, polystyrene, polyacrylate, acarboxyvinyl polymer, an acrylic resin copolymer resin, hydroxycellulose, hydroxymethyl cellulose, polyvinyl alcohol,polyvinylpyrrolidone, cellulose acetate, methyl cellulose, andcarboxymethyl cellulose. Among these, a water-insoluble resin ispreferable in order to prevent dissolution in dampening water at thetime of development.

Further, it is preferable that the binder contains at least one selectedfrom the group consisting of polyurethane, an acrylic resin,polystyrene, and polyethylene.

According to the (Aspect A1), it is preferable that the particles andthe binder respectively contain at least one selected from the groupconsisting of polyurethane, an acrylic resin, polystyrene, andpolyethylene.

As the binder contained in the resin layer according to the (Aspect A2),polymer compounds which are the same as the polymer compounds containedin the protrusions described below are exemplified, and the same appliesto the preferred aspect thereof.

Further, according to the (Aspect A2), from the viewpoint of preventingdesorption of protrusions, it is preferable that the binder contained inthe resin layer and the polymer compound contained in the protrusionsrespectively contain the same resin.

In the present disclosure, the expression “the resins are the same aseach other” means that the resins are of the same type, such aspolyurethane, an acrylic resin, polystyrene, and polyethylene, and it isnot necessary that all constitutional units in the resins are the sameas each other.

<<Sp Value>>

According to the (Aspect A1), a difference in the solubility parameter(SP value) between the particles and the binder is preferably 4MPa^(1/2) or less and more preferably 2 MPa^(1/2) or less.

In the present disclosure, the solubility parameter (SP value) is avalue [unit: MPa^(1/2)] acquired using an Okitsu method. The Okitsumethod is one of known methods of calculating the SP value and isdescribed in Journal of the Adhesion Society of Japan Vol. 29, No. 6(1993), p. 249 to 259.

—Other Components—

The resin layer of the present disclosure may contain components otherthan the particles and the binder.

Examples of other components include known additives such assurfactants.

[Protrusions]

It is preferable that the protrusions according to the (Aspect A2)contain a polymer compound as a main component. In the presentdisclosure, the main component indicates a component whose content ratio(% by mass) is the highest.

—Polymer Compound—

From the viewpoints of the development delay resistance and the platefeeding property of taking out a precursor from a laminate, suppressionof falling of particles, the polymer compound used for the protrusionsmay contain at least one selected from the group consisting of a novolakresin such as a phenol formaldehyde resin, an m-cresol formaldehyderesin, a p-cresol formaldehyde resin, an m-/p-mixed cresol formaldehyderesin, or a phenol/cresol (any of m-, p-, and m-/p-mixed)-mixedformaldehyde resin, a resol resin, pyrogallol, an acetone resin, anepoxy resin, a saturated copolymer polyester resin, a phenoxy resin, apolyvinyl acetal resin, a vinylidene chloride copolymer resin,polybutene, polybutadiene, polyamide, an unsaturated copolymer polyesterresin, polyurethane, polyurea, polyimide, polysiloxane, polycarbonate,chlorinated polyethylene, an aldehyde condensation resin of alkylphenol, polyvinyl chloride, polyvinylidene chloride, polystyrene,polyacrylate, a carboxyvinyl polymer, an acrylic resin copolymer resin,hydroxy cellulose, hydroxymethyl cellulose, polyvinyl alcohol,polyvinylpyrrolidone, cellulose acetate, methyl cellulose, andcarboxymethyl cellulose.

Among these, from the viewpoint that the developability is excellenteven in a case where desorbed protrusions are moved to the imagerecording layer, a water-soluble polymer is more preferable. Specificexamples thereof include polyacrylate, a carboxyvinyl polymer, anacrylic resin copolymer resin, hydroxy cellulose, hydroxymethylcellulose, polyvinyl alcohol, modified polyvinyl alcohol,polyvinylpyrrolidone, cellulose acetate, methyl cellulose, andcarboxymethyl cellulose.

As the modified polyvinyl alcohol, acid-modified polyvinyl alcoholcontaining a carboxy group or a sulfo group is preferably used.Specifically, the modified polyvinyl alcohol described in JP2005-250216Aor JP2006-259137A is suitable.

The shape and the height of the protrusions are not particularly limitedas long as the arithmetic average height Sa is in a range of 0.3 μm to20 μm, and the average height thereof is preferably in a range of 0.5 μmto 20 μm.

A method of forming stripe-like protrusions (stripe coated film) is notparticularly limited, and the protrusions can be easily formed byapplying a composition that contains at least one selected from thegroup consisting of particles and resins according to at least onesystem selected from the group consisting of a bar coating system, anink jet printing system, a gravure printing system, a screen printingsystem, a spray coating system, and a slot die coating system.

A method of forming dot-like protrusions (dot coated film) is notparticularly limited, and the protrusions can be easily formed byapplying a composition that contains at least one selected from thegroup consisting of particles and resins according to at least onesystem selected from the group consisting of a spray coating system, anink jet printing system, and a screen printing system.

A method of forming dashed line protrusions (dashed line coated film) isnot particularly limited, and the protrusions can be easily formed byapplying a composition that contains at least one selected from thegroup consisting of particles and resins according to at least onesystem selected from the group consisting of an ink jet printing systemand a screen printing system.

<Preferred Aspect of Front Surface>

In the lithographic printing plate precursor according to the presentdisclosure, an aspect for achieving the arithmetic average height Sa ofthe front surface is not particularly limited, and preferred examplesthereof include aspects in (Aspect B1) to (Aspect B4) described below.

(Aspect B1): The image recording layer is the outermost layer, containsat least one kind of particles having an average particle diameter of0.5 μm to 20 μm, and contains two or more kinds of particles havingdifferent average particle diameters.

(Aspect B2): A protective layer is provided on the image recording layeras the outermost layer, and the protective layer contains at least onekind of particles having an average particle diameter of 0.5 μm to 20μm.

(Aspect B3): The image recording layer is the outermost layer, and aplurality of protrusions containing a polymer compound as a maincomponent are provided on the image recording layer.

(Aspect B4): A protective layer is provided on the image recording layeras the outermost layer, and a plurality of protrusions containing apolymer compound as a main component are provided on the protectivelayer.

Preferred examples of the method for obtaining the lithographic printingplate precursor according to the (Aspect B1) include a method of addingparticles to a composition for forming an image recording layer.

Preferred examples of the method for obtaining the lithographic printingplate precursor according to the (Aspect B2) include a method of addingparticles to a composition for forming a protective layer.

Preferred examples of the method for obtaining the lithographic printingplate precursor according to the (Aspect B3) or (Aspect B4) include amethod of coating the surface of the outermost layer with a compositioncontaining at least one selected from the group consisting of particlesand a polymer compound to form protrusions.

Examples of the particles used in the (Aspect B1) to (Aspect B4) includethe particles used in the (Aspect A1) and (Aspect A2) described above.

Examples of the polymer compound used in the (Aspect B3) or (Aspect B4)include the polymer compound used in the (Aspect A2) described above.

<Support>

The lithographic printing plate precursor according to the presentdisclosure includes a hydrophilized aluminum support.

As the support used in the lithographic printing plate precursoraccording to the present disclosure, a known support is used. Among theexamples, an aluminum plate which has been subjected to an anodizationtreatment is preferable and an aluminum plate which has been subjectedto a roughening treatment and an anodization treatment is morepreferable.

The roughening treatment and the anodization treatment can be performedaccording to a known method.

The aluminum plate can be subjected to a treatment appropriatelyselected from an expansion treatment or a sealing treatment ofmicropores of an anodized film described in JP2001-253181A orJP2001-322365A or a surface hydrophilization treatment using alkalimetal silicate described in U.S. Pat. Nos. 2,714,066A, 3,181,461A,3,280,734A, and 3,902,734A or polyvinyl phosphonic acid described inU.S. Pat. Nos. 3,276,868A, 4,153,461A, and 4,689,272A as necessary.

The center line average roughness Ra of the support is preferably in arange of 0.10 μm to 1.2 μm.

[Preferred Aspect of Support]

According to a preferred aspect, for example, the aluminum support (analuminum support according to the present example will be also referredto as a “support A”) used in the present disclosure is an aluminumsupport including an aluminum plate and an aluminum anodized filmdisposed on the aluminum plate, the anodized film is positioned closerto the image recording layer than to the aluminum plate, the anodizedfilm has micropores extending in a depth direction from the surface ofthe image recording layer side, and the average diameter of themicropores in the surface of the anodized film is in a range of 7 nm to150 nm.

FIG. 1 is a schematic cross-sectional view illustrating an embodiment ofan aluminum support 12 a. The aluminum support 12 a has a laminatedstructure in which an aluminum plate 18 and an aluminum anodized film 20a (hereinafter, also simply referred to as an “anodized film 20 a”) arelaminated in this order. Further, the anodized film 20 a in the aluminumsupport 12 a is positioned closer to an image recording layer 16 sidethan to the aluminum plate 18. In other words, it is preferable that thelithographic printing plate precursor according to the presentdisclosure includes at least the aluminum plate, the anodized film, andthe image recording layer in this order.

—Anodized Film—

Hereinafter, a preferred aspect of the anodized film 20 a will bedescribed.

The anodized film 20 a is a film to be prepared on a surface of thealuminum plate 18 by performing an anodization treatment, and this filmis substantially perpendicular to the film surface and has extremelyfine micropores 22 a uniformly distributed. The micropores 22 a extendalong the thickness direction (the aluminum plate 18 side) from thesurface (the surface of the anodized film 20 a on a side opposite to aside where the aluminum plate 18 side) of the anodized film 20 a on theimage recording layer 16 side.

The average diameter (average opening diameter) of the micropores 22 ain the surface of the anodized film 20 a is preferably in a range of 7nm to 150 nm. From the viewpoint of the balance between the printingdurability, stain resistance, and image visibility, the average diameterthereof is preferably in a range of 10 nm to 100 nm, more preferably ina range of 15 nm to 60 nm, still more preferably in a range of 20 nm to50 nm, and particularly preferably in a range of 25 nm to 40 nm. Thediameter inside the pore may be wider or narrower than the surfacelayer.

In a case where the average diameter thereof is 7 nm or greater, theprinting durability and image visibility are further excellent. Further,in a case where the average diameter thereof is 150 nm or less, theprinting durability is further excellent.

The average diameter of micropores 22 a is calculated as an arithmeticaverage value obtained by observing 4 sheets (N=4) of the surfaces ofthe anodized film 20 a using a field emission scanning electronmicroscope (FE-SEM) at a magnification of 150000, measuring thediameters of 50 sites of micropores present in a range of 400×600 nm² inthe obtained four sheets of images, and averaging the values.

Further, in a case where the shape of the micropores 22 a is notcircular, an equivalent circle diameter is used. The “equivalent circlediameter” is a diameter of a circle obtained by assuming the shape of anopening portion of a micropore in the surface of the anodized film as acircle having the same projected area as the projected area of theopening portion.

The depth of the micropores 22 a is not particularly limited, but ispreferably in a range of 10 nm to 3000 nm, more preferably in a range of50 nm to 2000 nm, and still more preferably 300 nm to 1600 nm.

Further, the depth thereof is a value obtained by capturing (150000times) an image of a cross section of the anodized film 20 a, measuringthe depth of 25 or more micropores 22 a, and averaging the obtainedvalues.

The shape of the micropores 22 a is not particularly limited, and theshape thereof in FIG. 2 may be a substantially straight tubular shape,but may be a conical shape whose diameter decreases toward the depthdirection (thickness direction). Further, the shape of the bottomportion of the micropores 22 a is not particularly limited, but may be acurved shape (projection) or a planar shape.

The value of the brightness L* in the L*a*b* color system of the surfaceof the aluminum support 12 a on a side of the image recording layer 16(the surface of the anodized film 20 a on a side of the image recordinglayer 16) is in a range of 70 to 100. Here, from the viewpoint that thebalance between the printing durability and the image visibility isfurther excellent, the value thereof is preferably in a range of 75 to100 and more preferably in a range of 75 to 90.

The brightness L* is measured using a color difference meter Spectro Eye(manufactured by X-Rite Inc.).

The range of a steepness a45 representing the area ratio of a portionhaving an inclining degree of 45° or greater obtained by extracting acomponent with a wavelength of 0.2 μm to 2 μm in the surface of theanodized film 20 a on a side of the image recording layer 16 is notparticularly limited, but is preferably 25% or less, more preferably 20%or less, and still more preferably 18% or less from the viewpoints ofthe stain resistance and the deinking capability at the time of beingleft to stand. The lower limit thereof is not particularly limited, butis 5% or greater in many cases.

The steepness a45 is a factor representing the surface shape and is avalue acquired according to the following procedures (1) to (3).

(1) The surface shape is measured to acquire three-dimensional data.

The surface shape of the aluminum support 12 a on the anodized film 20 aside is measured using an atomic force microscope (AFM) to acquirethree-dimensional data.

The measurement is performed under the following conditions.Specifically, the aluminum support 12 a is cut into a size of 1 cm² andset on a horizontal sample stand that is provided on a piezo scanner, acantilever is allowed to approach the surface of the sample, scanning isperformed in the XY direction when reaching a region where atomic forceworks, and the unevenness of the sample is captured by the displacementof the piezo in the Z direction. A piezo scanner capable of performingscanning a distance of 150 μm in the XY direction and a distance of 10μm in the Z direction is used as the piezo scanner. A cantilever havinga resonance frequency of 120 kHz to 150 kHz and a sprint frequency of 12N/m to 20 N/m (SI-DF20, manufactured by Nanoprobes Inc.) is used in adynamic force mode (DFM) as the cantilever. Further, by carrying out theleast squares approximation of the acquired three-dimensional data, theslight inclination of the sample is corrected to acquire a referencesurface.

During the measurement, 512×512 points in an area having a size of 25μm×25 μm on the surface are measured. The resolution in the XY directionis 1.9 μm, the resolution in the Z direction is 1 nm, and the scanningspeed is 60 μm/sec.

(2) The correction is performed.

In the calculation of the steepness a45, a component having a wavelengthof 0.2 μm to 2 μm is selected from the three-dimensional data which hasbeen acquired in (1) described above and is corrected. Due to thiscorrection, in a case where a surface of an aluminum support or the likeused in the lithographic printing plate precursor which has significantunevenness is scanned using a probe of an AFM, a noise occurring in acase where the probe strikes an edge portion of a projection and springsso that a portion other than a pointed end of the probe is brought intocontact with a wall surface of a deep depression can be eliminated.

The correction is carried out by performing fast Fourier transformationon the three-dimensional data acquired in (1) described above to acquirethe frequency distribution, selecting a component having a wavelength of0.2 μm to 2 μm, and performing Fourier inverse transformation.

(3) The steepness a45 is calculated.

Three points adjacent to one another are extracted using thethree-dimensional data (f(x, y)) obtained by performing correction in(2) described above, an angle between a small triangle formed of thesethree points and the reference surface is calculated for all pieces ofdata to acquire the inclining degree distribution curve. In addition,the sum of the area of the small triangle is acquired and this area isset as the actual area. Based on the inclining degree distributioncurve, the steepness a45 (unit: %) which is a ratio of the area of aportion having an inclining degree of 45° or greater to the actual areais calculated.

The range of a specific surface area ΔS which is a value acquired by thefollowing Equation (i) based on a geometric measurement area S₀ and anactual area S_(x) acquired according to an approximation three pointmethod from the three-dimensional data to be obtained by measuring512×512 points in an area having a size of 25 μm×25 μm on the surface ofthe anodized film 20 a on the image recording layer 16 side using anatomic force microscope is not particularly limited, and is 15% orgreater in many cases. From the viewpoints of excellent stainresistance, deinking capability at the time of being left to stand, andimage visibility, the specific surface area ΔS is preferably 20% orgreater, more preferably in a range of 20% to 40%, and still morepreferably 25% to 35%.

ΔS=(S _(x) −S ₀)/S ₀×100(%)  (i)

In the measurement of ΔS described above, the three-dimensional data(f(x, y)) is obtained according to the same procedures as in (1) that isto be performed at the time of calculating the steepness a45.

Next, three points adjacent to one another are extracted using thethree-dimensional data (f(x, y)) obtained in the above-described manner,the sum of the area of the small triangle formed of these three pointsis acquired, and this area is set as an actual area S_(x). The specificsurface area ΔS is acquired by Equation (i) described above based on theactual area S_(x) and the geometric measurement area S₀.

In the support A, an aspect (hereinafter, the support according to theabove-described aspect is also referred to as a “support B”) in whichthe micropores are formed of large-diameter pores extending to aposition at a depth of 10 nm to 1000 nm from the surface of the anodizedfilm and small-diameter pores communicating with the bottom oflarge-diameter pores and extending from a position at a depth of 20 nmto 2000 nm from the communication position, the average diameter of thelarge-diameter pores in the surface of the anodized film is in a rangeof 15 nm to 150 nm, and the average diameter of the small-diameter poresin the communication position is 13 nm or less is preferablyexemplified.

FIG. 2 is a schematic cross-sectional view illustrating anotherembodiment of the aluminum support 12 a other than the supportillustrated in FIG. 1. The support B is an aspect of the aluminumsupport 12 a illustrated in FIG. 2.

In FIG. 2, the aluminum support 12 b includes an aluminum plate 18 andan anodized film 20 b having micropores 22 b formed of large-diameterpores 24 and small-diameter pores 26.

The micropores 22 b in the anodized film 20 b are formed oflarge-diameter pores 24 extending to a position at a depth (depth D: seeFIG. 2) of 10 nm to 1000 nm from the surface of the anodized film andsmall-diameter pores 26 communicating with the bottom of large-diameterpores 24 and extending from a position at a depth of 20 nm to 2000 nmfrom the communication position.

Hereinafter, the large-diameter pores 24 and the small-diameter pores 26will be described in detail.

The average diameter of the large-diameter pores 24 in the surface ofthe anodized film 20 b is greater than 10 nm to 100 nm, which is thesame as the average diameter of the micropores 22 a in the surface ofthe anodized film 20 a described above, and the preferable range is thesame as described above.

The method of measuring the average diameter of the large-diameter pores24 in the surface of the anodized film 20 b is the same as the method ofmeasuring the average diameter of the micropores 22 a in the surface ofthe anodized film 20 a.

The bottom of the large-diameter pores 24 is positioned at a depth of 10nm to 1000 nm (hereinafter, also referred to as a depth D) from thesurface of the anodized film. In other words, the large-diameter pores24 are pores extending from the surface of the anodized film to aposition at a depth of 10 nm to 1000 nm in the depth direction(thickness direction). The depth is preferably in a range of 10 nm to200 nm.

Further, the depth thereof is a value obtained by capturing (150000times) an image of a cross section of the anodized film 20 b, measuringthe depth of 25 or more large-diameter pores 24, and averaging theobtained values.

The shape of the large-diameter pores 24 is not particularly limited,and examples thereof include a substantially straight tubular shape(substantially cylindrical shape) and a conical shape whose diameterdecreases toward the depth direction (thickness direction). Among these,a substantially straight tubular shape is preferable.

The small-diameter pores 26, as illustrated in FIG. 2, are porescommunicating with the bottom of the large-diameter pores 24 andextending from the communication position to the depth direction(thickness direction).

The average diameter of the small-diameter pores 26 in the communicationposition is preferably 13 nm or less. Further, the average diameterthereof is preferably 11 nm or less and more preferably 10 nm or less.The lower limit thereof is not particularly limited, but is 5 nm orgreater in many cases.

The average diameter of small-diameter pores 26 is calculated as anarithmetic average value obtained by observing 4 sheets (N=4) of thesurfaces of the anodized film 20 a using a field emission scanningelectron microscope (FE-SEM) at a magnification of 150000, measuring thediameters of micropores (small-diameter pores) present in a range of 400nm×600 nm in the obtained four sheets of images, and averaging thevalues. In a case where the depth of the large-diameter pores is large,the average diameter of small-diameter pores may be acquired by cutting(for example, cutting the upper portion using argon gas) the upperportion (a region where large-diameter pores are present) of theanodized film 20 b as necessary and observing the surface of theanodized film 20 b using the above-described FE-SEM.

Further, in a case where the shape of the small-diameter pores 26 is notcircular, an equivalent circle diameter is used. The “equivalent circlediameter” is a diameter of a circle obtained by assuming the shape of anopening portion of a micropore as a circle having the same projectedarea as the projected area of the opening portion.

The bottom of the small-diameter pores 26 is in a position extendingfrom the communication position with the large-diameter pores 24 to adirection at a depth of 20 nm to 2000 nm. In other words, thesmall-diameter pores 26 are pores extending from the communicationposition with the large-diameter pores 24 to the depth direction(thickness direction), and the depth of the small-diameter pores 26 isin a range of 20 nm to 2000 nm. Further, the depth is preferably in arange of 500 nm to 1500 nm.

In addition, the depth thereof is a value obtained by capturing (50000times) an image of a cross section of the anodized film 20 b, measuringthe depth of 25 or more small-diameter pores, and averaging the obtainedvalues.

The shape of the small-diameter pores 26 is not particularly limited,and examples thereof include a substantially straight tubular shape(substantially cylindrical shape) and a conical shape whose diameterdecreases toward the depth direction. Among these, a substantiallystraight tubular shape is preferable.

[Method of Producing Aluminum Support]

As the method of producing an aluminum support included in thelithographic printing plate precursor according to the presentdisclosure, for example, a production method of sequentially performingthe following steps is preferable.

(Roughening treatment step) A step of performing a roughening treatmenton an aluminum plate

(Anodization treatment step) A step of anodizing the aluminum platewhich has been subjected to the roughening treatment

(Pore widening treatment step) A step of widening the diameter ofmicropores in the anodized film by bringing the aluminum plate havingthe anodized film obtained in the anodization treatment step intocontact with an acid aqueous solution or an alkali aqueous solution

Hereinafter, the procedures of each step will be described in detail.

—Roughening Treatment Step—

The roughening treatment step is a step of performing a rougheningtreatment including an electrochemical roughening treatment on a surfaceof an aluminum plate. It is preferable that the present step isperformed before the anodization treatment step described below, but maynot be performed in a case where the surface of the aluminum platealready has a preferable surface shape.

The roughening treatment may be carried out by performing only anelectrochemical roughening treatment, but may be carried out bycombining an electrochemical roughening treatment and a mechanicalroughening treatment and/or a chemical roughening treatment.

In a case where the mechanical roughening treatment is combined with theelectrochemical roughening treatment, it is preferable that theelectrochemical roughening treatment is performed after the mechanicalroughening treatment.

It is preferable that the electrochemical roughening treatment isperformed in an aqueous solution mainly containing nitric acid orhydrochloric acid using the direct current or the alternating current.

The method of performing the mechanical roughening treatment is notparticularly limited, and the methods described in JP1975-040047B(JP-S50-040047B) are exemplified.

The chemical roughening treatment is also not particularly limited, andknown methods are exemplified.

It is preferable that a chemical etching treatment described below isperformed after the mechanical roughening treatment.

The chemical etching treatment to be performed after the mechanicalroughening treatment is performed in order to smooth an edge portion ofthe uneven shape of the surface of the aluminum plate, prevent the inkfrom being caught during printing, improve the stain resistance of theprinting plate, and remove unnecessary matter such as abrasive materialparticles remaining on the surface.

Examples of the chemical etching treatment include etching carried outusing an acid and etching carried out using an alkali, and a chemicaletching treatment (hereinafter, also referred to as an “alkali etchingtreatment”) carried out using an alkali aqueous solution is exemplifiedas a particularly excellent method in terms of etching efficiency.

An alkali agent used for the alkali aqueous solution is not particularlylimited, and examples thereof include caustic soda, caustic potash,sodium metasilicate, soda carbonate, soda aluminate, and soda gluconate.

The alkali aqueous solution may contain aluminum ions.

The concentration of the alkali agent in the alkali aqueous solution ispreferably 0.01% by mass or greater, more preferably 3% by mass orgreater, and preferably 30% by mass or less.

In a case where the alkali etching treatment is performed, it ispreferable that the chemical etching treatment (hereinafter, alsoreferred to as a “desmutting treatment”) is performed using an acidicaqueous solution at a low temperature in order to remove a productgenerated due to the alkali etching treatment.

The acid used for the acidic aqueous solution is not particularlylimited, and examples thereof include sulfuric acid, nitric acid, andhydrochloric acid. Further, the temperature of the acidic aqueoussolution is preferably in a range of 20° C. to 80° C.

It is preferable that the roughening treatment step is performedaccording to a method of performing the treatments shown in an A aspector a B aspect in order described below.

(A Aspect)

(2) A chemical etching treatment carried out using an alkali aqueoussolution (first alkali etching treatment)

(3) A chemical etching treatment carried out using an acidic aqueoussolution (first desmutting treatment)

(4) An electrochemical roughening treatment carried out using an aqueoussolution that mainly contains nitric acid (first electrochemicalroughening treatment)

(5) A chemical etching treatment carried out using an alkali aqueoussolution (second alkali etching treatment)

(6) A chemical etching treatment carried out using an acidic aqueoussolution (second desmutting treatment)

(7) An electrochemical roughening treatment carried out in an aqueoussolution that mainly contains hydrochloric acid (second electrochemicalroughening treatment)

(8) A chemical etching treatment carried out using an alkali aqueoussolution (third alkali etching treatment)

(9) A chemical etching treatment carried out using an acidic aqueoussolution (third desmutting treatment)

(B Aspect)

(10) A chemical etching treatment carried out using an alkali aqueoussolution (fourth alkali etching treatment)

(11) A chemical etching treatment carried out using an acidic aqueoussolution (fourth desmutting treatment)

(12) An electrochemical roughening treatment carried out using anaqueous solution that mainly contains hydrochloric acid (thirdelectrochemical roughening treatment)

(13) A chemical etching treatment carried out using an alkali aqueoussolution (fifth alkali etching treatment)

(14) A chemical etching treatment carried out using an acidic aqueoussolution (fifth desmutting treatment)

The mechanical roughening treatment (1) may be performed before thetreatment (2) of the A aspect described above or before the treatment(10) of the B aspect described above, as necessary.

The amount of the aluminum plate to be dissolved in the first alkalietching treatment and the fourth alkali etching treatment is preferablyin a range of 0.5 to 30 g/m² and more preferably in a range of 1.0 to 20g/m².

As the aqueous solution that mainly contains nitric acid used for thefirst electrochemical roughening treatment according to the A aspect, anaqueous solution used for an electrochemical roughening treatmentcarried out using the direct current or the alternating current isexemplified. For example, an aqueous solution obtained by addingaluminum nitrate, sodium nitrate, or ammonium nitrate to 1 to 100 g/L ofa nitric acid aqueous solution is exemplified.

As the aqueous solution that mainly contains hydrochloric acid used forthe second electrochemical roughening treatment according to the Aaspect and the third electrochemical roughening treatment according tothe B aspect, a typical aqueous solution used for an electrochemicalroughening treatment carried out using the direct current or thealternating current is exemplified. For example, an aqueous solutionobtained by adding 0 g/L to 30 g/L of sulfuric acid to a 1 g/L to 100g/L hydrochloric acid aqueous solution is exemplified. Further, nitrateions such as aluminum nitrate, sodium nitrate, and ammonium nitrate; andhydrochloride ions such as aluminum chloride, sodium chloride, andammonium chloride may be added to this solution.

The AC power source waveform of the electrochemical roughening treatmentmay use a sine wave, a square wave, a trapezoidal wave, and a triangularwave. The frequency is preferably in a range of 0.1 Hz to 250 Hz.

FIG. 3 is a graph showing an example of an alternating waveform currentwaveform diagram used for the electrochemical roughening treatment.

In FIG. 3, ta represents an anode reaction time, tc represents a cathodereaction time, tp represents a time taken for the current to reach thepeak from 0, Ia represents the peak current on an anode cycle side, andIc represents the peak current on a cathode cycle side. In thetrapezoidal wave, the time tp taken for the current to reach the peakfrom 0 is preferably in a range of 1 to 10 ms. As the preferableconditions for one cycle of the alternating current used for theelectrochemical roughening, a ratio tc/ta of the cathode reaction timetc to the anode reaction time ta of the aluminum plate is in a range of1 to 20, a ratio Qc/Qa of an electric quantity Qc at the time of thealuminum plate serving as an cathode to an electric quantity Qa at thetime of the aluminum plate serving as an anode is in a range of 0.3 to20, and the anode reaction time ta is in a range of 5 ms to 1000 ms. Thecurrent density is preferably in a range of 10 A/dm to 200 A/dm² in bothof an anode cycle side Ia and a cathode cycle side Ic of the current interms of the peak value of the trapezoidal wave. The value of Ic/Ia ispreferably in a range of 0.3 to 20. The total amount of the electricityused for the anode reaction of the aluminum plate at the time when theelectrochemical roughening is completed is preferably in a range of 25C/dm² to 1000 C/dm².

A device illustrated in FIG. 4 can be used for the electrochemicalroughening carried out using the alternating current.

FIG. 4 is a side view illustrating an example of a radial type cell inthe electrochemical roughening treatment carried out using thealternating current.

In FIG. 4, the reference numeral 50 represents a main electrolytic cell,the reference numeral 51 represents an AC power source, the referencenumeral 52 represents a radial drum roller, the reference numerals 53 aand 53 b represent a main pole, the reference numeral 54 represents anelectrolytic solution supply port, the reference numeral 55 representsan electrolytic solution, the reference numeral 56 represents a slit,the reference numeral 57 represents an electrolytic solution passage,the reference numeral 58 represents an auxiliary anode, the referencenumeral 60 represents an auxiliary anode cell, and the symbol Wrepresents an aluminum plate. In a case where two or more electrolyticcells are used, the electrolysis conditions may be the same as ordifferent from each other.

The aluminum plate W is wound around the radial drum roller 52 disposedby being immersed in the main electrolytic cell 50 and is electrolyzedby the main poles 53 a and 53 b connected to the AC power source 51 inthe transport process. The electrolytic solution 55 is supplied to theelectrolytic solution passage 57 disposed between the radial drum roller52 and the main pole 53 a and between the radial drum roller 52 and themain pole 53 b through the slit 56 from the electrolytic solution supplyport 54. The aluminum plate W which has been treated in the mainelectrolytic cell 50 is electrolyzed in the auxiliary anode cell 60. Theauxiliary anode 58 is disposed in the auxiliary anode cell 60 so as toface the aluminum plate W and the electrolytic solution 55 is suppliedso as to flow through the space between the auxiliary anode 58 and thealuminum plate W.

From the viewpoint of easily producing a predetermined printing plateprecursor, the amount of the aluminum plate to be dissolved in thesecond alkali etching treatment is preferably 1.0 g/m² or greater andmore preferably in a range of 2.0 g/m² to 10 g/m².

From the viewpoint of easily producing a predetermined printing plateprecursor, the amount of the aluminum plate to be dissolved in the thirdalkali etching treatment and the fourth alkali etching treatment ispreferably 0.01 to 0.8 g/m² and more preferably in a range of 0.05 to0.3 g/m².

In the chemical etching treatments (first to fifth desmuttingtreatments) carried out using an acidic aqueous solution, an acidicaqueous solution containing phosphoric acid, nitric acid, sulfuric acid,chromic acid, hydrochloric acid, or mixed acids obtained by mixing twoor more of these acids is suitably used.

The concentration of the acidic aqueous solution is preferably in arange of 0.5% to 60% by mass.

—Anodization Treatment Step—

The procedures of the anodization treatment step are not particularlylimited as long as the above-described micropores are obtained, andknown methods are exemplified.

In the anodization treatment step, an aqueous solution containingsulfuric acid, phosphoric acid, oxalic acid, and the like can be used asan electrolytic cell. For example, the concentration of the sulfuricacid is in a range of 100 to 300 g/L.

The conditions for the anodization treatment are appropriately setdepending on the electrolytic solution. As an example of the conditions,the liquid temperature is in a range of 5° C. to 70° C. (preferably in arange of 10° C. to 60° C.), the current density is in a range of 0.5 to60 A/dm² (preferably in a range of 5 to 60 A/dm²), the voltage is in arange of 1 to 100 V (preferably in a range of 5 to 50 V), theelectrolysis time is in a range of 1 to 100 seconds (preferably in arange of 5 to 60 seconds), and the coating amount is in a range of 0.1to 5 g/m² (preferably in a range of 0.2 to 3 g/m²).

—Pore Widening Treatment—

The pore widening treatment is a treatment (pore diameter wideningtreatment) of widening the diameter (pore diameter) of microporespresent in the anodized film formed by the above-described anodizationtreatment step.

The pore widening treatment can be performed by bringing the aluminumplate obtained in the anodization treatment step into contact with anacid aqueous solution or an alkali aqueous solution. The method ofbringing the aluminum plate into contact with the solution is notparticularly limited, and examples thereof include an immersion methodand a spray method.

<Image Recording Layer>

The lithographic printing plate precursor according to the presentdisclosure includes a water-soluble or water-dispersible negative typeimage recording layer on the support.

In the present disclosure, the term “water-soluble” means that 0.5 g orgreater of a substance is dissolved in 100 g of water at 20° C., and thewater-soluble layer may be a layer which is dissolved by an amount of0.5 g or greater in 100 g of water at 20° C. Further, in the presentdisclosure, the term “water-dispersible” means that a substance isuniformly dispersed in water at 20° C., and the water-dispersible layerindicates a layer which can be uniformly dispersed in water at 20° C.

It is preferable that the image recording layer in the presentdisclosure is an image recording layer according to any of the followingfirst to fifth aspects.

First aspect: An infrared absorbing agent, a polymerizable compound, anda polymerization initiator are contained.

Second aspect: An infrared absorbing agent and thermoplastic polymerparticles are contained.

Third aspect: In the first aspect, polymer particles or a microgel isfurther contained.

Fourth aspect: In the first aspect, thermoplastic polymer particles arefurther contained.

Fifth aspect: In the fourth aspect, a microgel is further contained.

According to the first aspect or the second aspect, it is possible toobtain a lithographic printing plate precursor that has excellentprinting durability of a lithographic printing plate to be obtained.

According to the third aspect, it is possible to obtain a lithographicprinting plate precursor having excellent developability (particularly,on-press developability).

According to the fourth aspect, it is possible to obtain a lithographicprinting plate precursor having excellent printing durability.

According to the fifth aspect, it is possible to obtain a lithographicprinting plate precursor having excellent printing durability.

According to a preferred aspect of the lithographic printing plateprecursor of the present disclosure, the image recording layer is animage recording layer (hereinafter, also referred to as an “imagerecording layer A”) containing an infrared absorbing agent, apolymerization initiator, a polymerizable compound, and a binderpolymer.

According to another preferred aspect of the lithographic printing plateprecursor of the present disclosure, the image recording layer is animage recording layer (hereinafter, also referred to as an “imagerecording layer B”) containing an infrared absorbing agent, apolymerization initiator, a polymerizable compound, and a polymercompound having a particle shape.

According to a still another preferred aspect of the lithographicprinting plate precursor of the present disclosure, the image recordinglayer is an image recording layer (hereinafter, also referred to as an“image recording layer C”) containing an infrared absorbing agent andthermoplastic polymer particles.

[Image Recording Layer A]

The image recording layer A contains an infrared absorbing agent, apolymerization initiator, a polymerizable compound, and a binderpolymer. Hereinafter, the constituent components of the image recordinglayer A will be described.

—Infrared Absorbing Agent—

An infrared absorbing agent has a function of converting absorbedinfrared rays into heat, a function of electron transfer to apolymerization initiator described below through excitation by infraredrays, and/or a function of energy transfer. As the infrared absorbingagent used in the present disclosure, a coloring agent or a pigmenthaving maximum absorption at a wavelength of 760 nm to 1,200 nm ispreferable and a coloring agent having maximum absorption at awavelength of 760 to 1,200 nm is more preferable.

As the coloring agent, coloring agents described in paragraphs 0082 to0088 of JP2014-104631A can be used.

The average particle diameter of the pigment is preferably in a range of0.01 μm to 1 μm and more preferably in a range of 0.01 μm to 0.5 μm. Aknown dispersion technique used to produce inks or toners can be usedfor dispersion of the pigment. The details are described in “LatestPigment Application Technology” (CMC Publishing Co., Ltd., 1986) and thelike.

The infrared absorbing agent may be used alone or in combination of twoor more kinds thereof.

The content of the infrared absorbing agent is preferably in a range of0.05% by mass to 30% by mass, more preferably in a range of 0.1% by massto 20% by mass, and particularly preferably in a range of 0.2% by massto 10% by mass with respect to total mass of the image recording layer.

—Polymerization Initiator—

The polymerization initiator indicates a compound that initiates andpromotes polymerization of a polymerizable compound. As thepolymerization initiator, a known thermal polymerization initiator, acompound having a bond with small bond dissociation energy, or aphotopolymerization initiator can be used. Specifically, radicalpolymerization initiators described in paragraphs 0092 to 0106 ofJP2014-104631A can be used.

Preferred examples of compounds in the polymerization initiators includeonium salts. Among these, iodonium salts and sulfonium salts areparticularly preferable. Specific preferred examples of the compounds ineach of the salts are the compounds described in paragraphs 0104 to 0106of JP2014-104631A.

The content of the polymerization initiator is preferably in a range of0.1% by mass to 50% by mass, more preferably in a range of 0.5% by massto 30% by mass, and particularly preferably in a range of 0.8% by massto 20% by mass with respect to the total mass of the image recordinglayer. When the content thereof is in the above-described range,improved sensitivity and improved stain resistance of a non-image areaat the time of printing are obtained.

—Polymerizable Compound—

A polymerizable compound is an addition polymerizable compound having atleast one ethylenically unsaturated bond and is selected from compoundshaving preferably at least one and more preferably two or more terminalethylenically unsaturated bonds. These have chemical forms such as amonomer, a pre-polymer, that is, a dimer, a trimer, an oligomer, and amixture of these. Specifically, polymerizable compounds described inparagraphs 0109 to 0113 of JP2014-104631A can be used.

Among the examples described above, from the viewpoint that the balancebetween hydrophilicity associated with developability (particularly,on-press developability) and polymerization ability associated withprinting durability is excellent, isocyanuric acid ethyleneoxide-modified acrylates such as tris(acryloyloxyethyl) isocyanurate andbis(acryloyloxyethyl)hydroxyethyl isocyanurate are particularlypreferable.

The details of the structures of these polymerizable compounds, whetherto be used alone or in combination, and the usage method such as theaddition amount can be arbitrarily set according to the finalperformance design of a lithographic printing plate precursor. Thecontent of the above-described polymerizable compound to be used ispreferably in a range of 5% by mass to 75% by mass, more preferably in arange of 10% by mass to 70% by mass, and particularly preferably in arange of 15% by mass to 60% by mass with respect to the total mass ofthe image recording layer.

—Binder Polymer—

A binder polymer can be mainly used to improve the film hardness of theimage recording layer. As the binder polymer, known polymers of therelated art can be used and polymers having coated-film properties arepreferable. Among examples thereof, an acrylic resin, a polyvinyl acetalresin, and a polyurethane resin are preferable.

Preferred examples of the binder polymers include polymers having across-linking functional group in the main or side chain, preferably inthe side chain, for improving coated-film strength of an image area asdescribed in JP2008-195018A. Cross-linking occurs between polymermolecules by a cross-linking group so that curing is promoted.

Preferred examples of the cross-linking functional group include anethylenically unsaturated group such as a (meth)acryl group, a vinylgroup, an allyl group, or a styryl group and an epoxy group, and thecross-linking functional groups can be introduced into a polymer by apolymer reaction or copolymerization. For example, a reaction between anacrylic polymer having a carboxy group in the side chain thereof orpolyurethane and glycidyl methacrylate or a reaction between a polymerhaving an epoxy group and ethylenically unsaturated group-containingcarboxylic acid such as methacrylic acid can be used.

The content of the cross-linking group in the binder polymer ispreferably in a range of 0.1 mmol to 10.0 mmol, more preferably in arange of 0.25 mmol to 7.0 mmol, and particularly preferably in a rangeof 0.5 mmol to 5.5 mmol with respect to 1 g of the binder polymer.

Moreover, it is preferable that the binder polymer includes ahydrophilic group. The hydrophilic group contributes to impartingdevelopability (particularly, on-press developability) for the imagerecording layer. Particularly, in the coexistence of a cross-linkinggroup and a hydrophilic group, both of printing durability anddevelopability can be achieved.

Examples of the hydrophilic group include a hydroxy group, a carboxygroup, an alkylene oxide structure, an amino group, an ammonium group,an amide group, a sulfo group, and a phosphoric acid group. Among these,an alkylene oxide structure having 1 to 9 alkylene oxide units having 2or 3 carbon atoms is preferable. A monomer having a hydrophilic groupmay be copolymerized in order to provide a hydrophilic group for abinder polymer.

In addition, in order to control the impressing property, a lipophilicgroup such as an alkyl group, an aryl group, an aralkyl group, or analkenyl group can be introduced into the binder polymer. For example, alipophilic group-containing monomer such as methacrylic acid alkyl estermay be copolymerized.

The weight-average molecular weight (Mw) of the binder polymer ispreferably 2,000 or greater, more preferably 5,000 or greater, and stillmore preferably in a range of 10,000 to 300,000.

The content of the binder polymer is preferably in a range of 3% by massto 90% by mass, more preferably in a range of 5% by mass to 80% by mass,and still more preferably in a range of 10% by mass to 70% by mass withrespect to the total mass of the image recording layer.

As a preferred example of the binder polymer, a polymer compound havinga polyoxyalkylene chain in the side chain is exemplified. In a casewhere the image recording layer contains a polymer compound having apolyoxyalkylene chain in the side chain (hereinafter, also referred toas a POA chain-containing polymer compound), permeability of dampeningwater is promoted and developability (particularly, on-pressdevelopability) is improved.

Examples of the resin constituting the main chain of the POAchain-containing polymer compound include an acrylic resin, a polyvinylacetal resin, a polyurethane resin, a polyurea resin, a polyimide resin,a polyamide resin, an epoxy resin, a methacrylic resin, a polystyreneresin, a novolak type phenolic resin, a polyester resin, syntheticrubber, and natural rubber. Among these, an acrylic resin isparticularly preferable.

Further, in the present disclosure, a “main chain” indicates relativelythe longest bonding chain in a molecule of a polymer compoundconstituting a resin and a “side chain” indicates a molecular chainbranched from the main chain.

The POA chain-containing polymer compound does not substantially containa perfluoroalkyl group. The expression “does not substantially contain aperfluoroalkyl group” means that the mass ratio of a fluorine atompresent as a perfluoroalkyl group in a polymer compound is less than0.5% by mass, and it is preferable that the polymer compound does notcontain a fluorine atom. The mass ratio of the fluorine atom is measuredby an elemental analysis method.

In addition, the “perfluoroalkyl group” is a group in which all hydrogenatoms of the alkyl group are substituted with fluorine atoms.

As alkylene oxide (oxyalkylene) in a polyoxyalkylene chain, alkyleneoxide having 2 to 6 carbon atoms is preferable, ethylene oxide(oxyethylene) or propylene oxide (oxypropylene) is more preferable, andethylene oxide is still more preferable.

The repetition number of the alkylene oxide in a polyoxyalkylene chain,that is, a polyalkylene oxide moiety is preferably in a range of 2 to 50and more preferably in a range of 4 to 25.

In a case where the repetition number of the alkylene oxide is 2 orgreater, the permeability of dampening water is sufficiently improved.Further, from the viewpoint that printing durability is not degraded dueto abrasion, it is preferable that the repetition number thereof is 50or less.

As the polyalkylene oxide moiety, structures described in paragraphs0060 to 0062 of JP2014-104631A are preferable.

The POA chain-containing polymer compound may have cross-linkingproperties in order to improve coated-film strength of an image area.Examples of the POA chain-containing polymer compounds havingcross-linking properties are described in paragraphs 0063 to 0072 ofJP2014-104631A.

The proportion of repeating units having a poly(alkylene oxide) moietyin the total repeating units constituting the POA chain-containingpolymer compound is not particularly limited, but is preferably in arange of 0.5% by mole to 80% by mole and more preferably in a range of0.5% by mole to 50% by mole. Specific examples of the POAchain-containing polymer compounds are described in paragraphs 0075 and0076 of JP2014-104631A.

As the POA chain-containing polymer compound, hydrophilic macromolecularcompounds such as polyacrylic acid and polyvinyl alcohol described inJP2008-195018A can be used in combination as necessary. Further, alipophilic polymer compound and a hydrophilic polymer compound can beused in combination.

In addition to the presence of the POA chain-containing polymer compoundin the image recording layer as a binder that plays a role of connectingimage recording layer components with each other, the specific polymercompound may be present in the form of a particle. In a case where thespecific polymer compound is present in the form of a particle, theaverage particle diameter is preferably in a range of 10 nm to 1,000 nm,more preferably in a range of 20 nm to 300 nm, and particularlypreferably in a range of 30 nm to 120 nm.

The content of the POA chain-containing polymer compound is preferablyin a range of 3% by mass to 90% by mass and more preferably in a rangeof 5% by mass to 80% by mass with respect to the total mass of the imagerecording layer. In a case where the content thereof is in theabove-described range, both of permeability of dampening water and imageformability can be reliably achieved.

Other preferred examples of the binder polymer include a polymercompound (hereinafter, also referred to as a “star type polymercompound”) which has a polymer chain bonded to a nucleus through asulfide bond by means of using a polyfunctional, in a range of hexa- todeca-functional, thiol as the nucleus and in which the polymer chain hasa polymerizable group. As the star type polymer compound, for example,compounds described in JP2012-148555A can be preferably used.

Examples of the star type polymer compound include compounds having apolymerizable group such as an ethylenically unsaturated bond in themain chain or in the side chain, preferably in the side chain, forimproving coated-film strength of an image area as described inJP2008-195018A. Cross-linking occurs between polymer molecules by apolymerizable group so that curing is promoted.

Preferred examples of the polymerizable group include an ethylenicallyunsaturated group such as a (meth)acryl group, a vinyl group, an allylgroup, or a styryl group and an epoxy group. Among these, from theviewpoint of polymerization reactivity, a (meth)acryl group, a vinylgroup, or a styryl group is more preferable and a (meth)acryl group isparticularly preferable. These groups can be introduced into a polymerby a polymer reaction or copolymerization. For example, a reactionbetween a polymer having a carboxy group in the side chain thereof andglycidyl methacrylate or a reaction between a polymer having an epoxygroup and ethylenically unsaturated group-containing carboxylic acidsuch as methacrylic acid can be used. These groups may be used incombination.

The content of the cross-linking group in the star type polymer compoundis preferably in a range of 0.1 mmol to 10.0 mmol, more preferably in arange of 0.25 mmol to 7.0 mmol, and particularly preferably in a rangeof 0.5 mmol to 5.5 mmol with respect to 1 g of the star type polymercompound.

Moreover, it is preferable that the star type polymer compound furtherincludes a hydrophilic group. The hydrophilic group contributes toproviding developability (particularly, on-press developability) for theimage recording layer. Particularly, in the coexistence of apolymerizable group and a hydrophilic group, both of printing durabilityand developability can be achieved.

Examples of the hydrophilic group include —SO₃M¹, —OH, —CONR¹R² (M¹represents a hydrogen atom, a metal ion, an ammonium ion, or aphosphonium ion, R¹ and R² each independently represent a hydrogen atom,an alkyl group, an alkenyl group, or an aryl group, and R¹ and R² may bebonded to each other to form a ring), —N⁺R³R⁴R⁵X⁻ (R³ to R⁵ eachindependently represent an alkyl group having 1 to 8 carbon atoms and X⁻represents a counter anion), —(CH₂CH₂O)_(n)R, and —(C₃H₆O)_(m)R.

In the above-described formulae, n and m each independently represent aninteger of 1 to 100 and R's each independently represent a hydrogen atomor an alkyl group having 1 to 18 carbon atoms.

Here, in a case where the star type polymer compound is a star typepolymer compound having a polyoxyalkylene chain (for example,—(CH₂CH₂O)_(n)R, and —(C₃H₆O)_(m)R) in the side chain, such a star typepolymer compound is a polymer compound having the above-describedpolyoxyalkylene chain in the side chain.

Among these hydrophilic groups, —CONR¹R², —(CH₂CH₂O)_(n)R, or—(C₃H₆O)_(m)R is preferable, —CONR¹R² or —(CH₂CH₂O)_(n)R is morepreferable, and —(CH₂CH₂O)_(n)R is particularly preferable. In—(CH₂CH₂O)_(n)R, n represents an integer of preferably 1 to 10 andparticularly preferably 1 to 4. Further, R represents more preferably ahydrogen atom or an alkyl group having 1 to 4 carbon atoms andparticularly preferably a hydrogen atom or a methyl group. Thesehydrophilic groups may be used in combination of two or more kindsthereof.

Further, it is preferable that the star type polymer compound does notsubstantially include a carboxylic acid group, a phosphoric acid group,or a phosphonic acid group. Specifically, the amount of these acidgroups is preferably less than 0.1 mmol/g, more preferably less than0.05 mmol/g, and particularly preferably 0.03 mmol/g or less. In a casewhere the amount of these acid groups is less than 0.1 mmol/g,developability is further improved.

In order to control impressing properties, a lipophilic group such as analkyl group, an aryl group, an aralkyl group, or an alkenyl group can beintroduced to the star type polymer compound. Specifically, a lipophilicgroup-containing monomer such as methacrylic acid alkyl ester may becopolymerized.

Specific examples of the star type polymer compound include compoundsdescribed in paragraphs 0153 to 0157 of JP2014-104631A.

The star type polymer compound can be synthesized, using a known method,by performing radical polymerization on the above-described monomersconstituting a polymer chain in the presence of the above-describedpolyfunctional thiol compound.

The weight-average molecular weight (Mw) of the star type polymercompound is preferably in a range of 5,000 to 500,000, more preferablyin a range of 10,000 to 250,000, and particularly preferably in a rangeof 20,000 to 150,000. In a case where the weight-average molecularweight thereof is in the above-described range, the developability(particularly, on-press developability) and the printing durability aremore improved.

The star type polymer compound may be used alone or in combination oftwo or more kinds thereof. Further, the star type polymer compound maybe used in combination with a typical linear binder polymer.

The content of the star type polymer compound is preferably in a rangeof 5% by mass to 95% by mass, more preferably in a range of 10% by massto 90% by mass, and particularly preferably in a range of 15% by mass to85% by mass with respect to the total mass of the image recording layer.

From the viewpoint of promoting the permeability of dampening water andimproving the developability (particularly, on-press developability),star type polymer compounds described in JP2012-148555A are particularlypreferable.

—Other Components—

The image recording layer A can contain other components describedbelow.

(1) Low-Molecular Weight Hydrophilic Compound

In order to improve the developability (particularly, on-pressdevelopability) without degrading the printing durability, the imagerecording layer may contain a low-molecular weight hydrophilic compound.

As the low-molecular weight hydrophilic compound, examples of awater-soluble organic compound include glycols such as ethylene glycol,diethylene glycol, triethylene glycol, propylene glycol, dipropyleneglycol, and tripropylene glycol and ether or ester derivatives thereof;polyols such as glycerin, pentaerythritol, and tris(2-hydroxyethyl)isocyanurate; organic amines such as triethanolamine, diethanolamine,and monoethanolamine and salts thereof; organic sulfonic acids such asalkylsulfonic acid, toluenesulfonic acid, and benzenesulfonic acid andsalts thereof; organic sulfamic acids such as alkyl sulfamic acid andsalts thereof; organic sulfuric acids such as alkyl sulfuric acid andalkyl ether sulfuric acid and salts thereof; organic phosphonic acidssuch as phenyl phosphonic acid and salts thereof; organic carboxylicacids such as tartaric acid, oxalic acid, citric acid, malic acid,lactic acid, gluconic acid, and amino acids and salts thereof; andbetaines.

Among these, it is preferable that the image recording layer contains atleast one selected from the group consisting of polyols, organicsulfates, organic sulfonates, and betaines.

Specific examples of the compounds of the organic sulfonates includecompounds described in paragraphs 0026 to 0031 of JP2007-276454A andparagraphs 0020 to 0047 of JP2009-154525A. The salt may be potassiumsalt or lithium salt.

Examples of the organic sulfate include compounds described inparagraphs 0034 to 0038 of JP2007-276454A.

As betaines, compounds having 1 to 5 carbon atoms of hydrocarbonsubstituents to nitrogen atoms are preferable. Specific examples thereofinclude trimethyl ammonium acetate, dimethyl propyl ammonium acetate,3-hydroxy-4-trimethyl ammonio butyrate, 4-(1-pyridinio)butyrate,1-hydroxyethyl-1-imidazolioacetate, trimethyl ammonium methanesulfonate, dimethyl propyl ammonium methane sulfonate,3-trimethylammonio-1-propane sulfonate, and 3-(1-pyridinio)-1-propanesulfonate.

Since the low-molecular weight hydrophilic compound has a smallstructure of a hydrophobic portion, hydrophobicity or coated-filmstrength of an image area is not degraded by dampening water permeatinginto an image recording layer exposed portion (image area) and inkreceptivity or printing durability of the image recording layer can bemaintained satisfactorily.

The amount of the low-molecular weight hydrophilic compounds to be addedto the image recording layer is preferably in a range of 0.5% by mass to20% by mass, more preferably in a range of 1% by mass to 15% by mass,and still more preferably in a range of 2% by mass to 10% by mass withrespect to the total mass of the image recording layer. In a case wherethe amount thereof is in the above-described range, excellentdevelopability (particularly, on-press developability) and printingdurability can be obtained.

These low-molecular weight hydrophilic compounds may be used alone or incombination of two or more kinds thereof.

(2) Oil Sensitizing Agent

In order to improve the impressing property, an oil sensitizing agentsuch as a phosphonium compound, a nitrogen-containing low-molecularweight compound, or an ammonium group-containing polymer can be used forthe image recording layer. Particularly, in a case where a protectivelayer contains an inorganic layered compound, the above-describedcompounds function as a surface coating agent of the inorganic layeredcompound and prevent a degradation in impressing property due to theinorganic layered compound during the printing.

The phosphonium compound, the nitrogen-containing low-molecular weightcompound, and the ammonium group-containing polymer are described inparagraphs 0184 to 0190 of JP2014-104631A in detail.

The content of the oil sensitizing agent is preferably in a range of0.01% by mass to 30.0% by mass, more preferably in a range of 0.1% bymass to 15.0% by mass, and still more preferably in a range of 1% bymass to 10% by mass with respect to the total mass of the imagerecording layer.

(3) Other Components

The image recording layer may further contain other components such as asurfactant, a coloring agent, a printing-out agent, a polymerizationinhibitor, a higher fatty acid derivative, a plasticizer, inorganicparticles, an inorganic layered compound, a co-sensitizer, and a chaintransfer agent. Specifically, the compounds and the addition amountsdescribed in paragraphs 0114 to 0159 of JP2008-284817A, paragraphs 0023to 0027 of JP2006-091479A, and paragraph 0060 of US2008/0311520A can bepreferably used.

—Formation of Image Recording Layer A—

The image recording layer A is formed by dispersing or dissolving eachof the above-described required components in a known solvent to preparea coating solution, coating a support with the coating solution directlyor through an undercoat layer using a known method such as a bar coatercoating method, and drying the resultant, as described in paragraphs0142 and 0143 of JP2008-195018A. The coating amount of the imagerecording layer (solid content) on the support to be obtained after thecoating and the drying varies depending on the applications thereof, butis preferably in a range of 0.3 g/m² to 3.0 g/m². In a case where thecoating amount thereof is in the above-described range, excellentsensitivity and excellent film-coating characteristics of the imagerecording layer are obtained.

[Image Recording Layer B]

The image recording layer B contains an infrared absorbing agent, apolymerization initiator, a polymerizable compound, and a polymercompound having a particle shape. Hereinafter, the constituentcomponents of the image recording layer B will be described.

Similarly, the infrared absorbing agent, the polymerization initiator,and the polymerizable compound described in the image recording layer Acan be used as an infrared absorbing agent, a polymerization initiator,and a polymerizable compound in the image recording layer B.

—Polymer Compound Having Particle Shape—

It is preferable that the polymer compound having a particle shape isselected from the group consisting of thermoplastic polymer particles,thermally reactive polymer particles, polymer particles having apolymerizable group, a microcapsule encapsulating a hydrophobiccompound, and a microgel (cross-linked polymer particle). Among these,polymer particles having a polymerizable group and a microgel arepreferable. According to a particularly preferred embodiment, thepolymer compound having a particle shape includes at least oneethylenically unsaturated polymerizable group. Because of the presenceof the polymer compound having a particle shape, effects of improvingthe printing durability of an exposed portion and the developability(particularly, on-press developability) of an unexposed portion areobtained.

Further, it is preferable that the polymer compound having a particleshape is a thermoplastic polymer particle.

Preferred examples of the thermoplastic polymer particles includehydrophobic thermoplastic polymer particles described in ResearchDisclosure No. 33303 on January, 1992, JP1997-123387A (JP-H09-123387A),JP1997-131850A (JP-H09-131850A), JP1997-171249A (JP-H09-171249A),JP1997-171250A (JP-H09-171250A), and EP931647B.

Specific examples of a polymer constituting thermoplastic polymerparticles include homopolymers or copolymers of monomers such asacrylate or methacrylate having structures of ethylene, styrene, vinylchloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethylmethacrylate, vinylidene chloride, acrylonitrile, vinyl carbazole, andpolyalkylene, and mixtures of these. Among these, polystyrene, styrene,a copolymer containing acrylonitrile, and polymethylmethacrylate aremore preferable. The average particle diameter of the thermoplasticpolymer particles is preferably in a range of 0.01 μm to 3.0 μm.

Examples of the thermally reactive polymer particles include polymerparticles having a thermally reactive group. The thermally reactivepolymer particles are cross-linked by a thermal reaction and havehydrophobic regions formed by a change in functional groups during thecross-linking.

As the thermally reactive group in polymer particles having a thermallyreactive group, a functional group that performs any reaction may beused as long as a chemical bond is formed, but a polymerizable group ispreferable. Preferred examples of the polymerizable group include anethylenically unsaturated group that performs a radical polymerizationreaction (such as an acryloyl group, a methacryloyl group, a vinylgroup, or an allyl group); a cationic polymerizable group (such as avinyl group, a vinyloxy group, an epoxy group, or an oxetanyl group); anisocyanate group that performs an addition reaction or a block bodythereof, an epoxy group, a vinyloxy group, and a functional group havingactive hydrogen atoms as the reaction partners of these (such as anamino group, a hydroxy group, or a carboxy group); a carboxy group thatperforms a condensation reaction and a hydroxy group or an amino groupas a reaction partner thereof; and an acid anhydride that performs aring opening addition reaction and an amino group or a hydroxy group asa reaction partner thereof.

The microcapsule is a microcapsule in which at least a part ofconstituent components of the image recording layer is encapsulated asdescribed in JP2001-277740A and JP2001-277742A. Further, the constituentcomponents of the image recording layer may be contained in a portionother than the microcapsule. Moreover, a preferred embodiment of theimage recording layer containing the microcapsule is an embodiment inwhich hydrophobic constituent components are encapsulated by amicrocapsule and hydrophilic constituent components are contained by aportion other than the microcapsule.

The microgel (cross-linked polymer particles) may contain a part of theconstituent components of the image recording layer in at least one ofthe surface or the inside thereof. From the viewpoints of image formingsensitivity and printing durability, a reactive microgel having aradical polymerizable group on the surface thereof is particularlypreferable.

The constituent components of the image recording layer can be made intomicrocapsules or microgel particles using a known method.

From the viewpoints of the printing durability, stain resistance, andstorage stability, it is preferable that the polymer compound having aparticle shape is obtained by reacting a polyvalent isocyanate compoundwhich is an adduct of a polyhydric phenol compound containing two ormore hydroxy groups in a molecule and isophorone diisocyanate with acompound containing an active hydrogen atom.

As the polyhydric phenol compound, a compound having a plurality ofbenzene rings containing a phenolic hydroxy group is preferable.

As the compound that contains a compound containing the above-describedactive hydrogen atom, a polyol compound or a polyamine compound ispreferable, a polyol compound is more preferable, and at least onecompound selected from the group consisting of propylene glycol,glycerin, and trimethylolpropane is still more preferable.

As the resin particles obtained by reacting the compound containing anactive hydrogen atom with the polyvalent isocyanate compound which is anadduct of a polyhydric phenol compound containing two or more hydroxygroups in a molecule and isophorone diisocyanate, polymer particlesdescribed in paragraphs 0032 to 0095 of JP2012-206495A are preferablyexemplified.

Further, from the viewpoints of the printing durability and the solventresistance, it is preferable that the polymer compound having a particleshape has a hydrophobic main chain and both of a constitutional unit (i)which contains a pendant-cyano group directly bonded to the hydrophobicmain chain and a constitutional unit (ii) which contains a pendant grouphaving a hydrophilic polyalkylene oxide segment.

As the hydrophobic main chain, an acrylic resin chain is preferablyexemplified.

Preferred examples of the pendant-cyano group include —[CH₂CH(C≡N)—] and—[CH₂C(CH₃)(C≡N)—].

Further, the constitutional unit having a pendant-cyano group can beeasily derived from an ethylene-based unsaturated monomer such asacrylonitrile or methacrylonitrile or a combination of these.

Further, as the alkylene oxide in the hydrophilic polyalkylene oxidesegment, ethylene oxide or propylene oxide is preferable and ethyleneoxide is more preferable.

The repetition number of alkylene oxide structures in the hydrophilicpolyalkylene oxide segment is preferably in a range of 10 to 100, morepreferably in a range of 25 to 75, and still more preferably in a rangeof 40 to 50.

As the resin particles which have a hydrophobic main chain and both of aconstitutional unit (i) containing a pendant-cyano group directly bondedto the hydrophobic main chain and a constitutional unit (ii) containinga pendant group having a hydrophilic polyalkylene oxide segment, thosedescribed in paragraphs 0039 to 0068 of JP2008-503365A are preferablyexemplified.

The average particle diameter of the polymer compound having a particleshape is preferably in a range of 0.01 μm to 3.0 μm, more preferably ina range of 0.03 μm to 2.0 μm, and still more preferably in a range of0.10 μm to 1.0 μm. In a case where the average particle diameter thereofis in the above-described range, excellent resolution and temporalstability are obtained.

The content of the polymer compound having a particle shape ispreferably in a range of 5% by mass to 90% by mass with respect to themass of the image recording layer.

—Other Components—

The image recording layer B can contain other components described inthe above-described image recording layer A as necessary.

—Formation of Image Recording Layer B—

The image recording layer B can be formed in the same manner as theimage recording layer A described above.

[Image Recording Layer C]

The image recording layer C contains an infrared absorbing agent andthermoplastic polymer particles. Hereinafter, the constituent componentsof the image recording layer C will be described.

—Infrared Absorbing Agent—

As the infrared absorbing agent contained in the image recording layerC, a dye or a pigment having maximum absorption at a wavelength of 760nm to 1,200 nm is preferable. A dye is more preferable.

As the dye, commercially available dyes and known dyes described in theliteratures (for example, “Dye Handbook” edited by The Society ofSynthetic Organic Chemistry, Japan, published in 1970, “Near InfraredAbsorbing Dyes” of “Chemical Industry”, p. 45 to 51, published on May,1986, and “Development and Market Trend of Functional Dyes in 1990's”Section 2.3 of Chapter 2 (CMC Publishing Co., Ltd., 1990)) and thepatents can be used. Specific preferred examples thereof includeinfrared absorbing dyes such as an azo dye, a metal complex salt azodye, a pyrazolone azo dye, an anthraquinone dye, a phthalocyanine dye, acarbonium dye, a quinone imine dye, a polymethine dye, and a cyaninedye.

Among these, infrared absorbing dyes having a water-soluble group areparticularly preferable from the viewpoint of addition to the imagerecording layer C.

Specific examples of the infrared absorbing dyes are described below,but the present disclosure is not limited thereto.

As the pigments, commercially available pigments and pigments describedin Color Index (C. I.) Handbook, “Latest Pigment Handbook” (edited byJapan Pigment Technology Association, 1977), “Latest Pigment ApplicationTechnology” (CMC Publishing Co., Ltd., 1986), and “Printing InkTechnology” (CMC Publishing Co., Ltd., 1984) can be used.

The particle diameter of the pigment is preferably in a range of 0.01 μmto 1 μm and more preferably in a range of 0.01 μm to 0.5 μm. A knowndispersion technique used to produce inks or toners can be used as amethod of dispersing the pigment. The details are described in “LatestPigment Application Technology” (CMC Publishing Co., Ltd., 1986).

The content of the infrared absorbing agent is preferably in a range of0.1% by mass to 30% by mass, more preferably in a range of 0.25% by massto 25% by mass, and particularly preferably in a range of 0.5% by massto 20% by mass with respect to the total mass of the image recordinglayer. In a case where the content thereof is in the above-describedrange, excellent sensitivity is obtained without damaging the filmhardness of the image recording layer.

—Thermoplastic Polymer Particles—

The glass transition temperature (Tg) of the thermoplastic polymerparticles is preferably in a range of 60° C. to 250° C. The Tg of thethermoplastic polymer particles is more preferably in a range of 70° C.to 140° C. and still more preferably in a range of 80° C. to 120° C.

Preferred examples of the thermoplastic polymer particles having a Tg of60° C. or higher include thermoplastic polymer particles described inResearch Disclosure No. 33303 on January, 1992, JP1997-123387A(JP-H09-123387A), JP1997-131850A (JP-H09-131850A), JP1997-171249A(JP-H09-171249A), JP1997-171250A (JP-H09-171250A), and EP931647B.

Specific examples thereof include homopolymers or copolymers formed ofmonomers such as ethylene, styrene, vinyl chloride, methyl acrylate,ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidenechloride, acrylonitrile, and vinyl carbazole, and mixtures of these.Among these, polystyrene, styrene, a copolymer containing styrene andacrylonitrile, and polymethylmethacrylate are preferable.

The average particle diameter of the thermoplastic polymer particles ispreferably in a range of 0.005 μm to 2.0 μm from the viewpoints of theresolution and the temporal stability. This value is used as the averageparticle diameter in a case where two or more kinds of thermoplasticpolymer particles are mixed with each other. The average particlediameter thereof is more preferably in a range of 0.01 μm to 1.5 μm andparticularly preferably in a range of 0.05 μm to 1.0 μm. Thepolydispersity in a case where two or more kinds of thermoplasticpolymer particles are mixed with each other is preferably 0.2 orgreater. The average particle diameter and the polydispersity arecalculated according to a laser light scattering method.

The thermoplastic polymer particles may be used in combination of two ormore kinds thereof. Specifically, at least two kinds of thermoplasticpolymer particles with different particle sizes or at least two kinds ofthermoplastic polymer particles with different glass transitiontemperatures (Tg) may be exemplified. In a case where two or more kindsof thermoplastic polymer particles are used in combination, coated-filmcuring properties of an image area are further improved and printingdurability in a case where a lithographic printing plate is obtained isfurther improved.

For example, in a case where thermoplastic polymer particles having thesame particle size are used, voids are present between the thermoplasticpolymer particles to some extent, the curing properties of thecoated-film are not desirable in some cases even in a case where thethermoplastic polymer particles are melted and solidified by imageexposure. Meanwhile, in a case where thermoplastic polymer particleshaving different particle sizes are used, the void volume between thethermoplastic polymer particles can be decreased and thus thecoated-film curing properties of the image area after image exposure canbe improved.

Further, in a case where thermoplastic polymer particles having the sameTg are used, the thermoplastic polymer particles are not sufficientlymelted and solidified and, accordingly, the coated-film curingproperties are not desirable in some cases when an increase intemperature of the image recording layer resulting from image exposureis insufficient. Meanwhile, in a case where thermoplastic polymerparticles having different glass transition temperatures (Tg) are used,the coated-film curing properties of the image area can be improved whenan increase in temperature of the image recording layer resulting fromimage exposure is insufficient.

In a case where two or more kinds of thermoplastic polymer particleshaving different glass transition temperatures (Tg) are used incombination, the Tg of at least one thermoplastic polymer particle ispreferably 60° C. or higher. At this time, a difference in Tg ispreferably 10° C. or higher and more preferably 20° C. or higher. Inaddition, the content of the thermoplastic polymer particles having a Tgof 60° C. or higher is preferably 70% by mass or greater with respect tothe total amount of all thermoplastic polymer particles.

The thermoplastic polymer particles may include a cross-linking group.In a case where thermoplastic polymer particles having a cross-linkinggroup are used, the cross-linking group is thermally reacted due to heatgenerated by an image-exposed portion, cross-linking occurs betweenpolymers, coated-film strength of an image area is improved, andprinting durability becomes more excellent. As the cross-linking group,a functional group, in which any reaction may occur, is not limited aslong as a chemical bond is formed, and examples thereof include anethylenically unsaturated group that performs a polymerization reaction(such as an acryloyl group, a methacryloyl group, a vinyl group, or anallyl group); an isocyanate group that performs an addition reaction ora block body thereof, and a group having active hydrogen atoms as thereaction partners of these (such as an amino group, a hydroxy group, ora carboxyl group); an epoxy group that performs an addition reaction andan amino group, a carboxyl group or a hydroxy group as reaction partnersthereof; a carboxyl group that performs a condensation reaction and ahydroxy group or an amino group; and an acid anhydride that performs aring opening addition reaction and an amino group or a hydroxy group.

Specific examples of the thermoplastic polymer particles having across-linking group include thermoplastic polymer fine particles havingcross-linking groups such as an acryloyl group, a methacryloyl group, avinyl group, an allyl group, an epoxy group, an amino group, a hydroxygroup, a carboxyl group, an isocyanate group, an acid anhydride, and agroup protecting these. These cross-linking groups may be introduced topolymers at the time of polymerization of particle polymers or may beintroduced using a polymer reaction after polymerization of particlepolymers.

In a case where a cross-linking group is introduced to a polymer at thetime of polymerization of polymer particles, it is preferable that amonomer having a cross-linking group may be subjected to an emulsionpolymerization or suspension polymerization. Specific examples of themonomer having a cross-linking group include allyl methacrylate, allylacrylate, vinyl methacrylate, vinyl acrylate, glycidyl methacrylate,glycidyl acrylate, 2-isocyanate ethyl methacrylate or block isocyanateresulting from alcohol thereof, 2-isocyanate ethyl acrylate or blockisocyanate resulting from alcohol thereof, 2-aminoethyl methacrylate,2-aminoethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethylacrylate, acrylic acid, methacrylic acid, maleic anhydride, bifunctionalacrylate, and bifunctional methacrylate.

Examples of the polymer reaction used in a case where a cross-linkinggroup is introduced after polymerization of polymer particles includepolymer reactions described in WO96/034316A.

Polymer particles may react with each other through a cross-linkinggroup or the thermoplastic polymer particles may react with a polymercompound or a low-molecular weight compound added to the image recordinglayer.

The content of the thermoplastic polymer particles is preferably in arange of 50% by mass to 95% by mass, more preferably in a range of 60%by mass to 90% by mass, and particularly preferably in a range of 70% bymass to 85% by mass with respect to the total mass of the imagerecording layer.

—Other Components—

The image recording layer C may contain other components as necessary.

As other components, a surfactant having a polyoxyalkylene group or ahydroxy group is preferably exemplified.

As a surfactant having a polyoxyalkylene group (hereinafter, alsoreferred to as a “POA group”) or a hydroxy group, a surfactant having aPOA group or a hydroxy group can be suitably used, but an anionicsurfactant or a non-ionic surfactant is preferable. Among anionicsurfactants or non-ionic surfactants having a POA group or a hydroxygroup, anionic surfactants or non-ionic surfactants having a POA groupare preferable.

As the POA group, a polyoxyethylene group, a polyoxypropylene group, ora polyoxybutylene group is preferable and a polyoxyethylene group isparticularly preferable.

The average degree of polymerization of an oxyalkylene group ispreferably in a range of 2 to 50 and more preferably in a range of 2 to20.

The number of hydroxy groups is preferably 1 to 10 and more preferablyin a range of 2 to 8. Here, the number of terminal hydroxy groups in theoxyalkylene group is not included in the number of hydroxy groups.

The anionic surfactant having a POA group is not particularly limited,and examples thereof include polyoxyalkylene alkyl ether carboxylates,polyoxyalkylene alkyl sulfosuccinates, polyoxyalkylene alkyl ethersulfuric acid ester salts, alkyl phenoxy polyoxyalkylene propylsulfonates, polyoxyalkylene alkyl sulfophenyl ethers, polyoxyalkylenearyl ether sulfuric acid ester salts, polyoxyalkylene polycyclicphenylether sulfuric acid ester salts, polyoxyalkylene styryl phenylether sulfuric acid ester salts, polyoxyalkylene alkyl ether phosphoricacid ester salts, polyoxyalkylene alkyl phenyl ether phosphoric acidester salts, and polyoxyalkylene perfluoroalkyl ether phosphoric acidester salts.

The anionic surfactant having a hydroxy group is not particularlylimited, and examples thereof include hydroxy carboxylates, hydroxyalkyl ether carboxylates, hydroxy alkane sulfonates, fatty acidmonoglyceride sulfuric acid ester salts, and fatty acid monoglycerideacid ester salts.

The content of the surfactant having a POA group or a hydroxy group ispreferably in a range of 0.05% by mass to 15% by mass and morepreferably in a range of 0.1% by mass to 10% by mass with respect to thetotal mass of the image recording layer.

Hereinafter, specific examples of the surfactant having a POA group or ahydroxy group will be described, but the present disclosure is notlimited thereto. A surfactant A-12 described below is a trade name ofZonyl FSP and available from Dupont. Further, a surfactant N-11described below is a trade name of Zonyl FSO 100 and available fromDupont. Further, m and n in A-12 each independently represent an integerof 1 or greater.

For the purpose of ensuring coating uniformity of the image recordinglayer, the image recording layer may contain an anionic surfactant thatdoes not have a polyoxyalkylene group or a hydroxy group.

The anionic surfactant is not particularly limited as long as theabove-described purpose is achieved. Among the examples of the anionicsurfactants, alkyl benzene sulfonic acid or a salt thereof, alkylnaphthalene sulfonic acid or a salt thereof, (di)alkyl diphenyl ether(di)sulfonic acid or a salt thereof, or alkyl sulfuric acid ester saltis preferable.

The addition amount of the anionic surfactant that does not have apolyoxyalkylene group or a hydroxy group is preferably in a range of 1%by mass to 50% by mass and more preferably in a range of 1% by mass to30% by mass with respect to the total mass of the surfactant which has apolyoxyalkylene group or a hydroxy group.

Hereinafter, specific examples of the anionic surfactant that does nothave a polyoxyalkylene group or a hydroxy group will be described, butthe present disclosure is not limited thereto.

Further, for the purpose of coating uniformity of the image recordinglayer, a non-ionic surfactant that does not have a polyoxyalkylene groupor a hydroxy group or a fluorine surfactant may be used. For example,fluorine surfactants described in JP1987-170950A (JP-S62-170950A) arepreferably used.

The image recording layer may contain a hydrophilic resin. Preferredexamples of the hydrophilic resin include resins having hydrophilicgroups such as a hydroxy group, a hydroxyethyl group, a hydroxypropylgroup, an amino group, an aminoethyl group, an aminopropyl group, acarboxy group, a carboxylate group, a sulfo group, a sulfonate group,and a phosphoric acid group.

Specific examples of the hydrophilic resin include gum Arabic, casein,gelatin, a starch derivative, carboxy methyl cellulose and sodium saltthereof, cellulose acetate, sodium alginate, vinyl acetate-maleic acidcopolymers, styrene-maleic acid copolymers, polyacrylic acids and saltsof these, polymethacrylic acids and salts of these, a homopolymer and acopolymer of hydroxy ethyl methacrylate, a homopolymer and a copolymerof hydroxy ethyl acrylate, a homopolymer and a copolymer of hydroxypropyl methacrylate, a homopolymer and a copolymer of hydroxy propylacrylate, a homopolymer and a copolymer of hydroxy butyl methacrylate, ahomopolymer and a copolymer of hydroxy butyl acrylate, polyethyleneglycols, hydroxy propylene polymers, polyvinyl alcohols, hydrolyzedpolyvinyl acetate having a degree of hydrolysis of preferably at least60% and more preferably at least 80%, polyvinyl formal, polyvinylbutyral, polyvinylpyrrolidone, a homopolymer and a copolymer ofacrylamide, a homopolymer and a copolymer of methacrylamide, and ahomopolymer and a copolymer of N-methylol acrylamide.

The weight-average molecular weight of the hydrophilic resin ispreferably 2,000 or greater from the viewpoints of obtaining sufficientcoated-film strength or printing durability.

The content of the hydrophilic resin is preferably in a range of 0.5% bymass to 50% by mass and more preferably in a range of 1% by mass to 30%by mass with respect to the total mass of the image recording layer.

The image recording layer may contain inorganic particles other thanthose for forming unevenness described above. Preferred examples of theinorganic particles include silica, alumina, magnesium oxide, titaniumoxide, magnesium carbonate, calcium alginate, and a mixture of these.The inorganic particles can be used for the purpose of improvingcoated-film strength.

The average particle diameter of the inorganic particles is preferablyin a range of 5 nm to 10 μm and more preferably in a range of 10 nm to 1μm. In a case where the average particle diameter thereof is in theabove described range, the thermoplastic polymer particles are stablydispersed, the film hardness of the image recording layer issufficiently held, and a non-image area with excellent hydrophilicity inwhich printing stain is unlikely to occur can be formed.

The inorganic particles are available as commercially available productssuch as a colloidal silica dispersion and the like.

The content of the inorganic particles is preferably in a range of 1.0%by mass to 70% by mass and more preferably in a range of 5.0% by mass to50% by mass with respect to the total mass of the image recording layer.

The image recording layer may contain a plasticizer in order to provideflexibility for a coated film. Examples of the plasticizer includepolyethylene glycol, tributyl citrate, diethyl phthalate, dibutylphthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate,tributyl phosphate, trioctyl phosphate, and tetrahydrofurfuryl oleate.

The content of the plasticizer is preferably in a range of 0.1% by massto 50% by mass and more preferably in a range of 1% by mass to 30% bymass with respect to the total mass of the image recording layer.

In a case where polymer particles having a thermally reactive functionalgroup (cross-linking group) are used for the image recording layer, acompound that starts or promotes a reaction of the thermally reactivefunctional group (cross-linking group) can be added to the imagerecording layer as necessary. As the compound that starts or promotes areaction of the thermally reactive functional group, a compound thatgenerates a radical or a cation by heating may be exemplified. Examplesof the compound include a lophine dimer, a trihalomethyl compound, aperoxide, an azo compound, onium salts including diazonium salts anddiphenyl iodonium salts, acyl phosphine, and imide sulfonate. The amountof the compound to be added to the image recording layer is preferablyin a range of 1% by mass to 20% by mass and more preferably in a rangeof 1% by mass to 10% by mass with respect to the total mass of the imagerecording layer. In a case where the amount thereof is in theabove-described range, the developability (particularly, on-pressdevelopability) is not degraded and excellent effects for starting orpromoting a reaction are obtained.

—Formation of Image Recording Layer C—

The image recording layer C is formed by dissolving or dispersing eachof the above-described required components in a suitable solvent toprepare a coating solution, coating a support with the coating solutiondirectly or through an undercoat layer. As the solvent, water or a mixedsolvent of water and an organic solvent is used, and a mixed solvent ofwater and an organic solvent is preferable from the viewpoint of theexcellent surface state after coating. Since the amount of the organicsolvent varies depending on the type of organic solvent, the amountthereof cannot be specified unconditionally, but the amount of theorganic solvent in the mixed solvent is preferably in a range of 5% byvolume to 50% by volume. Here, it is necessary that the amount of theorganic solvent to be used is set such that the thermoplastic polymerparticles are not aggregated. The concentration of solid contents of theimage recording layer coating solution is preferably in a range of 1% bymass to 50% by mass.

As the organic solvent used as a solvent of the coating solution, awater-soluble organic solvent is preferable. Specific examples thereofinclude an alcohol solvent such as methanol, ethanol, propanol,isopropanol, or 1-methoxy-2-propanol, a ketone solvent such as acetoneor methyl ethyl ketone, a glycol ether solvent such as ethylene glycoldimethyl ether, γ-butyrolactone, N,N-dimethylformamide,N,N-dimethylacetamide, tetrahydrofuran, and dimethylsulfoxide.Particularly, an organic solvent having a boiling point of 120° C. orlower and a solubility (amount of a solvent to be dissolved in 100 g ofwater) of 10 g or greater in water is preferable and an organic solventhaving a solubility of 20 g or greater is more preferable.

As a coating method of the image recording layer coating solution,various methods can be used. Examples of the methods include a barcoater coating method, a rotary coating method, a spray coating method,a curtain coating method, a dip coating method, an air knife coatingmethod, a blade coating method, and a roll coating method. The coatingamount (solid content) of the image recording layer on the supportobtained after the coating and the drying varies depending on thepurpose thereof, but is preferably in a range of 0.5 g/m² to 5.0 g/m²and more preferably in a range of 0.5 g/m² to 2.0 g/m².

Hereinafter, other constituent elements of the lithographic printingplate precursor will be described.

<Undercoat Layer>

The lithographic printing plate precursor according to the presentdisclosure may be provided with an undercoat layer between the imagerecording layer and the support as necessary. Since bonding of thesupport to the image recording layer becomes stronger in an exposedportion and the support is easily separated from the image recordinglayer in an unexposed portion, the undercoat layer contributes toimprovement of the developability (particularly, on-pressdevelopability) without degrading the printing durability. Further, in acase of infrared laser exposure, the undercoat layer functions as a heatinsulating layer so that a degradation in sensitivity due to heat,generated by exposure, being diffused in the support is prevented.

Examples of the compound used for the undercoat layer include a silanecoupling agent having an ethylenic double bond reaction group, which canbe added and polymerized, described in JP1998-282679A (JP-H10-282679A);and a phosphorous compound having an ethylenic double bond reactiongroup described in JP1990-304441A (JP-H02-304441A). Preferred examplesthereof include polymer compounds having an adsorptive group which canbe adsorbed to the surface of the support, a hydrophilic group, and across-linking group, as described in JP2005-125749A and JP2006-188038A.As such a polymer compound, a copolymer of a monomer having anadsorptive group, a monomer having a hydrophilic group, and a monomerhaving a cross-linking group is preferable. Specific examples thereofinclude a copolymer of a monomer having an adsorptive group such as aphenolic hydroxy group, a carboxy group, —PO₃H₂, —OPO₃H₂, —CONHSO₂—,—SO₂NHSO₂—, or —COCH₂COCH₃, a monomer having a hydrophilic group such asa sulfo group, and a monomer having a polymerizable cross-linking groupsuch as a methacryl group or an allyl group. The polymer compound mayinclude a cross-linking group introduced by forming salts between apolar substituent of the polymer compound and a compound that includes asubstituent having the opposite charge and an ethylenically unsaturatedbond. Further, monomers other than the monomers described above,preferably hydrophilic monomers may be further copolymerized.

The content of the ethylenically unsaturated bond in the polymercompound for an undercoat layer is preferably in a range of 0.1 mmol to10.0 mmol and more preferably in a range of 2.0 mmol to 5.5 mmol withrespect to 1 g of the polymer compound.

The weight-average molecular weight of the polymer compound for anundercoat layer is preferably 5,000 or greater and more preferably in arange of 10,000 to 300,000.

For the purpose of preventing stain over time, the undercoat layer maycontain a chelating agent, a secondary or tertiary amine, apolymerization inhibitor, an amino group, a compound that includes anamino group or a functional group having polymerization inhibitingability and a group interacting with the surface of an aluminum support,and the like (for example, 1,4-diazabicyclo[2.2.2]octane (DABCO),2,3,5,6-tetrahydroxy-p-quinone, chloranil, sulfophthalic acid,hydroxyethyl ethylene diamine triacetic acid, dihydroxyethyl ethylenediamine diacetic acid, or hydroxyethyl imino diacetic acid) in additionto the compounds for an undercoat layer described above.

The undercoat layer is applied according to a known method. The coatingamount of the undercoat layer after being dried is preferably in a rangeof 0.1 mg/m² to 100 mg/m² and more preferably in a range of 1 mg/m² to30 mg/m².

<Protective Layer>

In the lithographic printing plate precursor, according to the presentdisclosure, a protective layer may be provided on the image recordinglayer as necessary. The protective layer has a function of suppressing areaction of inhibiting image formation through oxygen blocking, afunction of preventing generation of damage to the image recordinglayer, and a function of preventing ablation at the time of highilluminance laser exposure.

As the protective layer having such functions, a protective layerdescribed in paragraphs 0202 to 0204 of JP2014-104631A can be used.

The protective layer is applied according to a known method. The coatingamount of the protective layer after the drying is preferably in a rangeof 0.01 g/m² to 10 g/m², more preferably in a range of 0.02 g/m² to 3g/m², and particularly preferably in a range of 0.02 g/m² to 1 g/m².

The lithographic printing plate precursor can be produced by applying acoating solution of each configuration layer according to a typicalmethod, performing drying, and forming each configuration layer. Thecoating solution can be applied according to a die coating method, a dipcoating method, an air knife coating method, a curtain coating method, aroller coating method, a wire bar coating method, a gravure coatingmethod, or a slide coating method.

<Method of Producing Lithographic Printing Plate Precursor>

A method of producing the lithographic printing plate precursoraccording to the present disclosure is not particularly limited, but itis preferable that the method thereof includes a step of forming theimage recording layer on the aluminum support after one or more daysfrom an anodization treatment performed thereon.

In a case where the aluminum support after one or more days from ananodization treatment performed thereon is used, the development delayresistance (particularly, on-press development delay resistance) and theplate feeding property of taking out a precursor from a laminate becomefurther excellent even though the detailed mechanism is not clear.

In the method of producing the lithographic printing plate precursoraccording to the present disclosure, from the viewpoints of thedevelopment delay resistance and the plate feeding property of takingout a precursor from a laminate, it is preferable to use an aluminumsupport after one or more days from an anodization treatment performedthereon, it is more preferable to use an aluminum support after threedays to 1.5 years from an anodization treatment performed thereon, andstill more preferable to use an aluminum support after 7 days to 1 yearfrom an anodization treatment performed thereon.

Further, in a case where an undercoat layer is formed, from theviewpoints of the development delay resistance and the plate feedingproperty of taking out a precursor from a laminate, it is preferablethat the method of producing the lithographic printing plate precursoraccording to the present disclosure includes a step of forming theundercoat layer on the aluminum support after one or more days from ananodization treatment performed thereon.

(Lithographic Printing Plate Precursor Laminate and LithographicPrinting Plate Laminate)

The lithographic printing plate precursor laminate according to thepresent disclosure is a laminate obtained by laminating lithographicprinting plate precursors according to the present disclosure, and alaminate which is obtained by laminating a plurality of the lithographicprinting plate precursors according to the present disclosure, in whichthe outermost layer on the surface where the image recording layer isprovided and the outermost layer on the surface on the opposite side ofthe surface where the image recording layer is provided are laminated bybeing directly brought into contact with each other, is preferable.

Further, it is preferable that the lithographic printing plate precursorlaminate according to the present disclosure is a laminate obtained bylaminating a plurality of sheets of lithographic printing plateprecursors according to the present disclosure without interposinginterleaving paper therebetween.

The number of sheets of laminated precursors is not particularlylimited, but is preferably in a range of 2 sheets to 500 sheets.

The lithographic printing plate precursor laminate according to thepresent disclosure has excellent performance in any of adhesiveness,scratches, or bruises due to the specific surface roughness of thelithographic printing plate precursor according to the presentdisclosure, and dislocation in stacking of lithographic printing plateprecursors is unlikely to occur.

The lithographic printing plate laminate according to the presentdisclosure is a laminate obtained by laminating the lithographicprinting plates according to the present disclosure described below.

For example, in a case where there is an interval between several hoursto several days after the plate-making of the lithographic printingplate precursor according to the present disclosure before theinitiation of printing, the lithographic printing plate laminateaccording to the present disclosure is formed by staking a plurality ofobtained lithographic printing plates and allowing the stack to stand atan appropriate location.

The lithographic printing plate laminate according to the presentdisclosure has excellent performance in any of adhesiveness, scratches,or bruises due to the specific surface roughness of the lithographicprinting plate according to the present disclosure, and dislocation instacking of lithographic printing plates is unlikely to occur.

(Lithographic Printing Plate and Plate-Making Method Thereof andLithographic Printing Method)

The lithographic printing plate according to the present disclosure is alithographic printing plate obtained by plate-making the lithographicprinting plate precursor according to the present disclosure.

The plate-making method of the lithographic printing plate according tothe present disclosure is not particularly limited as long as the methodis a method of plate-making the lithographic printing plate precursoraccording to the present disclosure, and the method is a method ofplate-making the lithographic printing plate using the lithographicprinting plate precursor according to the present disclosure andperforming printing, and it is preferable that the method includes astep of image-exposing the lithographic printing plate precursoraccording to the present disclosure (also referred to as an “imageexposure step”); and a step of supplying at least any of printing ink ordampening water and removing an unexposed portion of an image recordinglayer on a printing press to prepare a lithographic printing plate (alsoreferred to as a “development treatment step”).

The above-described plate-making method is also referred to as an“on-press development system” below.

The lithographic printing method according to the present disclosure isa method of plate-making the lithographic printing plate using thelithographic printing plate precursor according to the presentdisclosure and performing printing, and it is preferable that the methodincludes a step of image-exposing the lithographic printing plateprecursor according to the present disclosure (also referred to as an“image exposure step”); a step of supplying at least any of printing inkor dampening water and removing an unexposed portion of an imagerecording layer on a printing press to prepare a lithographic printingplate (also referred to as a “development treatment step”); and a stepof performing printing using the obtained lithographic printing plate(also referred to as a “printing step”).

Further, in the lithographic printing plate precursor according to thepresent disclosure, the development treatment step is performed withoutperforming the image exposure step in a case of the key plate precursor.

<Image Exposure Step>

The image exposure of the lithographic printing plate precursor can beperformed in conformity with an image exposure operation for a typicallithographic printing plate precursor.

The image exposure is performed by laser exposure through a transparentoriginal picture having a line image, a halftone image, and the like orby laser beam scanning using digital data. The wavelength of a lightsource is preferably in a range of 700 nm to 1,400 nm. As the lightsource having a wavelength of 700 nm to 1,400 nm, a solid-state laser ora semiconductor laser that radiates infrared rays is preferable. Theoutput of the infrared laser is preferably 100 mW or greater, theexposure time per one pixel is preferably less than 20 microseconds, andthe irradiation energy quantity is preferably in a range of 10 mJ/cm² to300 mJ/cm². For the purpose of reducing the exposure time, it ispreferable to use a multi-beam laser device. The exposure mechanism maybe any of an internal drum system, an external drum system, and a flatbed system. The image exposure can be performed using a plate setteraccording to a usual method.

<Development Treatment Step>

The development step can be performed using a typical method. In a caseof on-press development, a printing ink receiving portion having alipophilic surface is formed by the image recording layer cured by lightexposure in the exposed portion of the image recording layer in a casewhere at least any of dampening water or printing ink is supplied to theimage-exposed lithographic printing plate precursor on a printing press.Meanwhile, in an unexposed portion, a non-cured image recording layer isdissolved or dispersed by supplied at least any of dampening water orprinting ink and then removed, a hydrophilic surface is exposed to theportion. As the result, dampening water is exposed and adheres to thehydrophilic surface, the printing ink is impressed on the imagerecording layer of the exposed region, and then the printing is started.

Here, either of dampening water or printing ink may be initiallysupplied to the surface of the lithographic printing plate precursor,but it is preferable that dampening water is initially supplied theretoby infiltrating dampening water so that the on-press developability ispromoted.

<Printing Step>

The printing using the obtained lithographic printing plate can beperformed according to a typical method. The printing can be performedby supplying desired printing ink and dampening water, as necessary, tothe lithographic printing plate.

The amount of the printing ink and dampening water to be supplied is notparticularly limited and may be appropriately set according to thedesired printing.

The method of supplying the printing ink and dampening water to thelithographic printing plate is not particularly limited and a knownmethod can be used.

The lithographic printing method according to the present disclosure mayinclude known steps other than the above-described steps. Examples ofother steps include a plate inspection step of confirming theorientation or position of the lithographic printing plate precursorbefore each step and a confirmation step of confirming the printed imageafter the development treatment step.

<Other Aspects>

Further, in the lithographic printing plate precursor according to thepresent disclosure, a lithographic printing plate can be prepared byperforming a development treatment using a developer by appropriatelyselecting a binder polymer or the like serving as a constituentcomponent of the image recording layer.

According to another aspect, it is preferable that the method ofplate-making a lithographic printing plate according to the presentdisclosure includes a step of image-exposing the lithographic printingplate precursor according to the present disclosure (also referred to asan “image exposure step”) and a development step of supplying adeveloper having a pH of 2 to 14 and removing the unexposed portion(also referred to as a “developer development step”).

The plate-making method is also referred to as a “developer treatmentsystem”.

Another aspect of the lithographic printing method according to thepresent disclosure relates to a method of plate-making for alithographic printing plate using the lithographic printing plateprecursor according to the present disclosure and performing printing,it is preferable that the lithographic printing method according to thepresent disclosure includes a step of image-exposing the lithographicprinting plate precursor according to the present disclosure (alsoreferred to as an “image exposure step”); a development step ofsupplying a developer having a pH of 2 to 14 and removing the unexposedportion (also referred to as a “developer development step”); and a stepof performing printing using the obtained lithographic printing plate(hereinafter, also referred to as a “printing step”).

[Image Exposure Step]

The image exposure step in the developer treatment system is the same asthe image exposure step in the on-press development system describedabove.

[Developer Treatment System]

In the lithographic printing plate precursor according to the presentdisclosure, a lithographic printing plate can be prepared by performinga development treatment using a developer by appropriately selecting abinder polymer or the like serving as a constituent component of theimage recording layer. The development treatment carried out using adeveloper includes an aspect (also referred to as a simple developmenttreatment) of using a developer having a pH of 2 to 11 which contains atleast one compound selected from the group consisting of a surfactantand a water-soluble polymer compound.

The development treatment and a gum liquid treatment step can besimultaneously performed using a method of allowing a developer tocontain a water-soluble polymer compound as necessary.

Accordingly, a post-water washing step is not particularly required, anda drying step can be performed after the development treatment and thegum liquid treatment are performed using one liquid and one step.Therefore, it is preferable that the development treatment using adeveloper is performed according to the method of preparing alithographic printing plate, including a step of performing adevelopment treatment on the image-exposed lithographic printing plateprecursor using a developer having a pH of 2 to 11. After thedevelopment treatment, it is preferable that the drying is performedafter the excessive developer is removed using a squeeze roller.

In other words, in the development step of the method of preparing alithographic printing plate according to the present disclosure, it ispreferable that the development treatment and the gum liquid treatmentare performed using one liquid and one step.

The expression “the development treatment and the gum liquid treatmentare performed using one liquid and one step” means that the developmenttreatment and the gum liquid treatment are performed in one step usingone liquid without separately performing the development treatment andthe gum liquid treatment as individual steps.

The development treatment can be suitably performed using an automaticdevelopment treatment device provided with developer supply means and arubbing member. As the rubbing member, an automatic developmenttreatment device provided with a rotary brush roll is particularlypreferable.

It is preferable that two or more rotary brush rolls are used. Further,it is preferable that an automatic development treatment device includesmeans for removing the excessive developer, such as a squeeze roller,and drying means such as a hot air device on the rear side of thedevelopment treatment device. Further, the automatic developmenttreatment device may include pre-heating means for performing a heatingtreatment on the image-exposed lithographic printing plate precursor onthe front side of the development treatment means.

The treatment carried out using such an automatic development treatmentdevice has an advantage that it is no longer necessary to deal withdevelopment scum derived from an image recording layer (a protectivelayer in a case where the lithographic printing plate precursor has aprotective layer) which is generated in a case of a so-called on-pressdevelopment treatment.

In a case where the development is carried out by performing a treatmentmanually, a method of allowing sponge or absorbent cotton to contain anaqueous solution, performing treatment while rubbing the entire platesurface, and drying the aqueous solution after the treatment iscompleted is suitably exemplified as the development treatment method.In a case of an immersion treatment, for example, a method of immersingthe lithographic printing plate precursor in a tray, a deep tank, or thelike containing an aqueous solution therein for approximately 60seconds, stirring the solution, and drying the aqueous solution whilerubbing the plate surface with absorbent cotton or sponge is suitablyexemplified.

It is preferable that a device capable of simplifying the structure andthe steps is used in the development treatment.

For example, in the alkali development treatment, a protective layer isremoved by the pre-water washing step, development is performed using analkali developer having a high pH, an alkali is removed by thepost-water washing step, the gum treatment is performed by a gum coatingstep, and drying is performed by a drying step. In the simpledevelopment treatment, development and gum coating can be simultaneouslyperformed using one liquid. Therefore, the post-water washing step andthe gum treatment step can be omitted, and it is preferable that thedrying step is performed as necessary after development and gum coating(gum liquid treatment) are performed using one liquid.

Further, it is preferable that removal of the protective layer,development, and gum coating are simultaneously performed using oneliquid without performing the pre-water washing step. Further, it ispreferable that the excessive developer is removed using a squeezeroller after the development and the gum coating and then drying isperformed.

The development treatment may be performed according to a method ofperforming immersion in a developer once or a method of performingimmersion twice or more times. Among these, a method of performingimmersion in the developer once or twice is preferable.

The immersion may be carried out by passing the exposed lithographicprinting plate precursor through a developer tank in which the developeris stored or spraying the developer onto the plate surface of theexposed lithographic printing plate precursor using a spray or the like.

Further, the development treatment is performed using one liquid (oneliquid treatment) even in a case where the lithographic printing plateprecursor is immersed in the developer twice or more times or in a casewhere the lithographic printing plate precursor is immersed, twice ormore times, in the same developer as described above or a developer(fatigue liquid) obtained by dissolving or dispersing components of theimage recording layer using the developer and the development treatment.

In the development treatment, it is preferable to use a rubbing memberand also preferable that a rubbing member such as a brush is installedin a developing bath which removes a non-image area of the imagerecording layer.

The development treatment can be performed by immersing the lithographicprinting plate precursor which has been subjected to the exposuretreatment and rubbing the plate surface with brushes or pumping up thetreatment liquid added to an external tank using a pump, spraying thedeveloper from a spray nozzle, and rubbing the plate surface withbrushes at a temperature of preferably 0° C. to 60° C. and morepreferably 15° C. to 40° C., according to a conventional method. Thesedevelopment treatments can be continuously performed plural times. Forexample, the development treatment can be performed by pumping up thedeveloper added to an external tank using a pump, spraying the developerfrom a spray nozzle, rubbing the plate surface with brushes, sprayingthe developer from the spray nozzle again, and rubbing the plate surfacewith the brushes. In a case where the development treatment is performedusing an automatic development treatment device, since the developerbecomes fatigued as the treatment amount increases, it is preferablethat the treatment capability is recovered using a replenisher or afresh developer.

The development treatment can also be performed using a gum coater or anautomatic development treatment device which has been known to be usedfor a presensitized (PS) plate and computer-to-plate (CTP) in therelated art. In a case where an automatic development treatment deviceis used, for example, any system from among a system of performing thetreatment by pumping the developer added to a developer tank or thedeveloper added to an external tank using a pump and spraying thedeveloper from a spray nozzle, a system of performing the treatment byimmersing a printing plate in a tank filled with the developer andtransporting the printing plate using a guide roller in the developer,and a so-called disposable treatment system, which is a system ofperforming the treatment by supplying the substantially unused developerby an amount required for each plate can be employed. In all systems, itis preferable that a rubbing mechanism using brushes or a molleton isprovided. For example, commercially available automatic developmenttreatment devices (Clean Out Unit C85/C125, Clean-Out Unit+C85/120, FCF85V, FCF 125V, FCF News (manufactured by Glunz & Jensen); and AzuraCX85, Azura CX125, and Azura CX150 (manufactured by AGFA GRAPHICS) canbe used. In addition, a device in which a laser exposure portion and anautomatic development treatment device portion are integrallyincorporated can also be used.

The components and the like of the developer used for the developmentstep will be described in detail.

—pH—

The pH of the developer is preferably in a range of 2 to 11, morepreferably in a range of 5 to 9, and still more preferably in a range of7 to 9. From the viewpoints of the developability and the dispersibilityof the image recording layer, it is advantageous that the value of thepH is set to be higher. However, from the viewpoints of the printabilityand suppression of stain, it is effective that the value of the pH isset to be low.

Here, the pH is a value obtained by performing measurement at 25° C.using a pH meter (model number: HM-31, manufactured by DKK-TOACorporation).

—Surfactant—

The developer may contain a surfactant such as an anionic surfactant, anon-ionic surfactant, a cationic surfactant, or an amphotericsurfactant.

From the viewpoint of blanket stain properties, it is preferable thatthe developer contains at least one selected from the group consistingof an anionic surfactant and an amphoteric surfactant.

Further, it is preferable that the developer contains a non-ionicsurfactant and more preferable that the developer contains at least oneselected from the group consisting of a non-ionic surfactant, an anionicsurfactant, and an amphoteric surfactant.

Preferred examples of the anionic surfactant include compoundsrepresented by Formula (I).

R¹—Y¹—X¹  (I)

In Formula (I), R¹ represents an alkyl group, a cycloalkyl group, analkenyl group, an aralkyl group, or an aryl group which may have asubstituent.

As the alkyl group, an alkyl group having 1 to 20 carbon atoms ispreferable, and preferred specific examples thereof include a methylgroup, an ethyl group, a propyl group, an n-butyl group, a sec-butylgroup, a hexyl group, a 2-ethylhexyl group, an octyl group, a decylgroup, a dodecyl group, a hexadecyl group, and a stearyl group.

The cycloalkyl group may be monocyclic or polycyclic. As the monocycliccycloalkyl group, a monocyclic cycloalkyl group having 3 to 8 carbonatoms is preferable, and a cyclopropyl group, a cyclopentyl group, acyclohexyl group, or a cyclooctyl group is more preferable. Preferredexamples of the polycyclic cycloalkyl group include an adamantyl group,a norbornyl group, an isobornyl group, a camphanyl group, adicyclopentyl group, an α-pinel group, and a tricyclodecanyl group.

As the alkenyl group, for example, an alkenyl group having 2 to 20carbon atoms is preferable, and preferred specific examples thereofinclude a vinyl group, an allyl group, a butenyl group, and acyclohexenyl group.

As the aralkyl group, for example, an aralkyl group having 7 to 12carbon atoms is preferable, and preferred specific examples thereofinclude a benzyl group, a phenethyl group, and a naphthylmethyl group.

As the aryl group, for example, an aryl group having 6 to 15 carbonatoms is preferable, and preferred specific examples thereof include aphenyl group, a tolyl group, a dimethylphenyl group, a2,4,6-trimethylphenyl group, a naphthyl group, an anthryl group, and a9,10-dimethoxyanthryl group.

As the substituent, a monovalent nonmetallic atom group excluding ahydrogen atom is used, and preferred examples thereof include a halogenatom (F, Cl, Br, or I), a hydroxy group, an alkoxy group, an aryloxygroup, an acyl group, an amide group, an ester group, an acyloxy group,a carboxy group, a carboxylic acid anion group, and a sulfonic acidanion group.

As specific examples of the alkoxy group in the substituent, a methoxygroup, an ethoxy group, a propyloxy group, an isopropyloxy group, abutyloxy group, a pentyloxy group, a hexyloxy group, a dodecyloxy group,a stearyloxy group, a methoxyethoxy group, a poly(ethyleneoxy) group,and a poly(propyleneoxy) group, respectively having 1 to 40 carbonatoms, are preferable; and these groups respectively having 1 to 20carbon atoms are more preferable. Examples of the aryloxy group includea phenoxy group, a tolyloxy group, a xylyloxy group, a mesityloxy group,a cumenyloxy group, a methoxyphenyloxy group, an ethoxyphenyloxy group,a chlorophenyloxy group, a bromophenyloxy group, and a naphthyloxygroup, respectively having 6 to 18 carbon atoms. Examples of the acylgroup include an acetyl group, a propanoyl group, a butanoyl group, abenzoyl group, and a naphthoyl group, respectively having 2 to 24 carbonatoms. Examples of the amide group include an acetamide group, apropionic acid amide group, a dodecanoic acid amide group, a palmiticacid amide group, a stearic acid amide group, a benzoic acid amidegroup, and a naphthoic acid amide group, respectively having 2 to 24carbon atoms. Examples of the acyloxy group include an acetoxy group, apropanoyloxy group, a benzoyloxy group, and a naphthoyloxy group,respectively having 2 to 20 carbon atoms. Examples of the ester groupinclude a methyl ester group, an ethyl ester group, a propyl estergroup, a hexyl ester group, an octyl ester group, a dodecyl ester group,and a stearyl ester group, respectively having 1 to 24 carbon atoms. Thesubstituent may be formed by combining two or more substituentsdescribed above.

X¹ represents a sulfonate group, a sulfate monoester group, acarboxylate group, or a phosphate group.

Y¹ represents a single bond, —C_(n)H_(2n)—,—C_(n-m)H_(2(n-m))OC_(m)H_(2m)—, —O—(CH₂CH₂O)_(n)—,—O—(CH₂CH₂CH₂O)_(n)—, —CO—NH—, or a divalent linking group formed bycombining two or more of these and satisfies the expressions of “n≥1”and “n≥m≥0”.

Among examples of the compound represented by Formula (I), from theviewpoint of scratch and stain resistance, a compound represented byFormula (I-A) or Formula (I-B) is preferable.

In Formulae (I-A) and (I-B), R^(A1) to R^(A10) each independentlyrepresent a hydrogen atom or an alkyl group, nA represents an integer of1 to 3, X^(A1) and X^(A2) each independently represent a sulfonategroup, a sulfate monoester group, a carboxylate group, or a phosphategroup, and Y^(A1) and Y^(A2) each independently represent a single bond,—C_(n)H_(2n)—, —C_(n-m)H_(2(n-m))OC_(m)H_(2m)—, —O—(CH₂CH₂O)_(n)—,—O—(CH₂CH₂CH₂O)_(n)—, —CO—NH—, or a divalent linking group formed bycombining two or more of these and satisfy the inequations of “n≥1” and“n≥m≥0”. The total number of carbon atoms in R^(A1) to R^(A5) or R^(A6)to R^(A10) and Y^(A1) and Y^(A2) is 3 or greater.

The total number of carbon atoms in R^(A1) to R^(A5) and Y^(1A) orR^(A6) to R^(A10) and Y^(A2) in the compound represented by Formula(I-A) or (I-B) is preferably 25 or less and more preferably in a rangeof 4 to 20. The structure of the above-described alkyl group may belinear or branched.

It is preferable that X^(A1) and X^(A2) in the compound represented byFormula (I-A) or (I-B) represent a sulfonate group or a carboxylategroup. Further, the salt structure in X^(A1) and X^(A2) is preferablefrom the viewpoint that the solubility of the alkali metal salt in awater-based solvent is particularly excellent. Among the saltstructures, a sodium salt or a potassium salt is particularlypreferable.

As the compound represented by Formula (I-A) or (I-B), the descriptionin paragraphs 0019 to 0037 of JP2007-206348A can be referred to.

As the anionic surfactant, the compounds described in paragraphs 0023 to0028 of JP2006-065321A can be suitably used.

The amphoteric surfactant used for the developer is not particularlylimited, and examples thereof include an amine oxide-based surfactantsuch as alkyl dimethylamine oxide; a betaine-based surfactant such asalkyl betaine, fatty acid amide propyl betaine, or alkyl imidazole; andan amino acid-based surfactant such as sodium alkylamino fatty acid.

Particularly, alkyl dimethylamine oxide which may have a substituent,alkyl carboxy betaine which may have a substituent, or alkylsulfobetaine which may have a substituent is preferably used. Specificexamples of these include compounds represented by Formula (2) inparagraph 0256 of JP2008-203359A, compounds represented by Formulae (I),(II), and (VI) in paragraph 0028 of JP2008-276166A, and compoundsdescribed in paragraphs 0022 to 0029 of JP2009-047927A.

As the amphoteric ion-based surfactant used for the developer, acompound represented by formula (1) or a compound represented by Formula(2) is preferable.

In Formulae (1) and (2), R¹ and R¹¹ each independently represent analkyl group having 8 to 20 carbon atoms or an alkyl group that containsa linking group having 8 to 20 carbon atoms.

R², R³, R¹², and R¹³ each independently represent a hydrogen atom, analkyl group, or a group containing an ethylene oxide structure.

R⁴ and R¹⁴ each independently represent a single bond or an alkylenegroup.

Further, two groups from among R¹, R², R³, and R⁴ may be bonded to eachother to form a ring structure, and two groups from among R¹¹, R¹², R¹³,and R¹⁴ may be bonded to each other to form a ring structure.

In the compound represented by Formula (1) or the compound representedby Formula (2), the hydrophobic portion becomes bigger as the totalnumber of carbon atoms increases, and the solubility in a water-baseddeveloper is decreased. In this case, the solubility is improved bymixing an organic solvent such as alcohol that assists dissolution withwater as a dissolution assistant, but the surfactant cannot be dissolvedwithin a proper mixing range in a case where the total number of carbonatoms becomes extremely large. Accordingly, the total number of carbonatoms of R¹ to R⁴ or to R¹⁴ is preferably in a range of 10 to 40 andmore preferably in a range of 12 to 30.

The alkyl group containing a linking group represented by R¹ or R¹¹ hasa structure in which a linking group is present between alkyl groups. Inother words, in a case where one linking group is present, the structurecan be represented by “-alkylene group-linking group-alkyl group”.Examples of the linking group include an ester bond, a carbonyl bond,and an amide bond. The structure may have two or more linking groups,but it is preferable that the structure has one linking group, and anamide bond is particularly preferable as the linking group. The totalnumber of carbon atoms of the alkylene group bonded to the linking groupis preferably in a range of 1 to 5. The alkylene group may be linear orbranched, but a linear alkylene group is preferable. The number ofcarbon atoms of the alkyl group bonded to the linking group ispreferably in a range of 3 to 19, and the alkyl group may be linear orbranched, but a linear alkyl group is preferable.

In a case where R² or R¹² represents an alkyl group, the number ofcarbon atoms thereof is preferably in a range of 1 to 5 and particularlypreferably in a range of 1 to 3. The alkyl group may be linear orbranched, but a linear alkyl group is preferable.

In a case where R³ or R¹³ represents an alkyl group, the number ofcarbon atoms thereof is preferably in a range of 1 to 5 and particularlypreferably in a range of 1 to 3. The alkyl group may be linear orbranched, but a linear alkyl group is preferable.

As the group containing an ethylene oxide structure represented by R³ orR¹³, a group represented by —R^(a)(CH₂CH₂O)nR^(b) is exemplified. Here,R^(a) represents a single bond, an oxygen atom, or a divalent organicgroup (preferably having 10 or less carbon atoms), R^(b) represents ahydrogen atom or an organic group (preferably having 10 or less carbonatoms), and n represents an integer of 1 to 10.

In a case where R⁴ and R¹⁴ represents an alkylene group, the number ofcarbon atoms thereof is preferably in a range of 1 to 5 and particularlypreferably in a range of 1 to 3. The alkylene group may be linear orbranched, but a linear alkylene group is preferable.

The compound represented by Formula (1) or the compound represented byFormula (2) has preferably an amide bond and more preferably an amidebond as a linking group represented by R¹ or R¹¹.

Representative examples of the compound represented by Formula (1) orthe compound represented by Formula (2) are as follows, but the presentdisclosure is not limited thereto.

The compound represented by Formula (1) or (2) can be synthesizedaccording to a known method. Further, commercially available productsmay be used. Examples of the commercially available products of thecompound represented by Formula (1) include SOFRAZOLINE LPB, SOFTAZOLINELPB-R, and VISTA MAP (manufactured by Kawaken Fine Chemicals Co., Ltd.),and TAKESAAF C-157L (manufactured by TAKEMOTO OIL & FAT Co., Ltd.).Examples of the commercially available products of the compoundrepresented by Formula (2) include SOFTAZOLINE LAO (manufactured byKawaken Fine Chemicals Co., Ltd.) and AMOGEN AOL (manufactured by DKSCo., Ltd.).

The amphoteric ion-based surfactant may be used alone or in combinationof two or more kinds thereof in a developer.

Examples of non-ionic surfactant include polyoxyethylene alkyl ethers,polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenylether, glycerin fatty acid partial esters, sorbitan fatty acid partialesters, pentaerythritol fatty acid partial esters, propylene glycolmonofatty acid ester, sucrose fatty acid partial ester, polyoxyethylenesorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acidpartial esters, polyethylene glycol fatty acid esters, polyglycerinfatty acid partial esters, polyoxyethylene glycerin fatty acid partialesters, polyoxyethylene diglycerins, fatty acid diethanolamides,N,N-bis-2-hydroxyalkylamines, polyoxyethyl ene alkylamine,triethanolamine fatty acid ester, trialkylamine oxide, polyoxyethylenealkyl phenyl ethers, and polyoxyethylene-polyoxypropylene blockcopolymers.

Further, acetylene glycol-based and acetylene alcohol-based oxyethyleneadducts, and fluorine-based surfactants can also be used. Thesesurfactants can be used in combination of two or more kinds thereof.

Particularly preferred examples of the non-ionic surfactant include anon-ionic aromatic ether-based surfactant represented by Formula (N1).

X^(N)—Y^(N)—O-(A¹)_(nB)-(A²)_(mB)-H  (N1)

In the formula, X^(N) represents an aromatic group which may have asubstituent, Y^(N) represents a single bond or an alkylene group having1 to 10 carbon atoms, A¹ and A² are different groups and represent anyof —CH₂CH₂O— or —CH₂CH(CH₃)O—, nB and mB each independently represent aninteger of 0 to 100, where both of nB and mB do not represent 0 at thesame time. Further, both of nB and mB do not represent 1 at the sametime in a case where any of nB or mB represents 0.

In the formula, examples of the aromatic group as X^(N) include a phenylgroup, a naphthyl group, and an anthranyl group. These aromatic groupsmay have a substituent. As the substituent, an organic group having 1 to100 carbon atoms is exemplified. Further, in the formula, this mayrepresent a random or block copolymer in a case where both of A and Bare present.

Specific examples of the organic group having 1 to 100 carbon atomsinclude fatty acid hydrocarbon groups and aromatic hydrocarbon groups,which may be saturated or unsaturated and linear or branched, such as analkyl group, an alkenyl group, an alkynyl group, an aryl group, anaralkyl group, an alkoxy group, an aryloxy group, a N-alkylamino group,a N,N-dialkylamino group, a N-arylamino group, a N,N-diarylamino group,a N-alkyl-N-arylamino group, an acyloxy group, a carbamoyloxy group, aN-alkylcarbamoyloxy group, a N-arylcarbamoyloxy group, a N,N-dialkylcarbamoyloxy group, a N,N-di arylcarbamoyloxy group, aN-alkyl-N-arylcarbamoyloxy group, an acylamino group, a N-alkylacylaminogroup, a N-arylacylamino group, an acyl group, an alkoxycarbonylaminogroup, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoylgroup, a N-alkylcarbamoyl group, a N,N-dialkylcarbamoyl group, aN-arylcarbamoyl group, a N,N-diarylcarbamoyl group, aN-alkyl-N-arylcarbamoyl group, a polyoxyalkylene chain, and theabove-described organic group to which a polyoxyalkylene chain isbonded. The alkyl group may be linear or branched.

Further, as the non-ionic surfactants, compounds described in paragraphs0030 to 0040 of JP2006-065321A can also be suitably used.

The cationic surfactant is not particularly limited, and knownsurfactants of the related art can be used. Examples thereof includealkylamine salts, quaternary ammonium salts, alkylimidazolinium salts,polyoxyethylene alkylamine salts, and a polyethylene polyaminederivative.

The surfactant may be used alone or in combination of two or more kindsthereof.

The content of the surfactant is preferably in a range of 1% by mass to25% by mass, more preferably in a range of 2% by mass to 20% by mass,still more preferably in a range of 3% by mass to 15% by mass, andparticularly preferably in a range of 5% by mass to 10% by mass withrespect to the total mass of the developer. In a case where the contentthereof is in the above-described range, the scratch and stainresistance is excellent, the dispersibility of the development scum isexcellent, and the ink impressing property of the lithographic printingplate to be obtained is excellent.

—Water-Soluble Polymer Compound—

From the viewpoints of adjusting the viscosity of the developer andprotecting the plate surface of the lithographic printing plate to beobtained, the developer may contain a water-soluble polymer compound.

Examples of the water-soluble polymer compound which can be contained inthe developer include soybean polysaccharides, modified starch, arabicgum, dextrin, a fiber derivative (such as carboxymethyl cellulose,carboxyethyl cellulose, or methyl cellulose) and a modified productthereof, pullulan, polyvinyl alcohol and a derivative thereof,polyvinylpyrrolidone, polyacrylamide and an acrylamide copolymer, avinyl methyl ether/maleic anhydride copolymer, a vinyl acetate/maleicanhydride copolymer, and a styrene/maleic anhydride copolymer.

As the soybean polysaccharides, those which have been known in therelated art can be used. For example, SOYAFIBE (trade name, manufacturedby FUJI OIL, CO., LTD.) can be used as a commercially available product,and various grades of products can be used. Preferred examples thereofinclude products in which the viscosity of a 10 mass % aqueous solutionis in a range of 10 mPa·s to 100 mPa·s.

As the modified starch, starch represented by Formula (III) ispreferable. Any of starch such as corn, potato, tapioca, rice, or wheatcan be used as the starch represented by Formula (III). The modificationof the starch can be performed according to a method of decomposing 5 to30 glucose residues per one molecule with an acid or an enzyme andadding oxypropylene to an alkali.

In the formula, the etherification degree (degree of substitution) is ina range of 0.05 to 1.2 per glucose unit, n represents an integer of 3 to30, and m represents an integer of 1 to 3.

Among the examples of the water-soluble polymer compound, soybeanpolysaccharides, modified starch, arabic gum, dextrin, carboxymethylcellulose, and polyvinyl alcohol are particularly preferable.

The water-soluble polymer compound can be used in combination of two ormore kinds thereof.

In a case where the developer contains a water-soluble polymer compound,the content of the water-soluble polymer compound is preferably 3% bymass or less and more preferably 1% by mass or less with respect to thetotal mass of the developer. In a case where the content thereof is inthe above-described range, the viscosity of the developer is moderate,and deposition of development scum and the like on a roller member of anautomatic development treatment device can be suppressed.

—Other Additives—

The developer used in the present disclosure may contain a wettingagent, a preservative, a chelate compound, an antifoaming agent, anorganic acid, an organic solvent, an inorganic acid, and an inorganicsalt in addition to those described above.

Suitable examples of the wetting agent include ethylene glycol,propylene glycol, triethylene glycol, butylene glycol, hexylene glycol,diethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, anddiglycerin. The wetting agent may be used alone or in combination of twoor more kinds thereof. The content of the wetting agent is preferably ina range of 0.1% by mass to 5% by mass with respect to the total mass ofthe developer.

Preferred examples of the preservative include phenol and a derivativethereof, formalin, an imidazole derivative, a sodium dehydroacetate,4-isothiazoline-3-one derivative, benzoisothiazolin-3-one,2-methyl-4-isothiazolin-3-one, a guanidine derivative, derivatives ofquaternary ammonium salts, pyridine, quinoline, and guanidine, diazine,a triazole derivative, oxazole, an oxazole derivative, nitrobromoalcohol-based 2-bromo-2-nitropropane-1,3-diol,1,1-dibromo-1-nitro-2-ethanol, and 1,1-dibromo-1-nitro-2-propane.

The amount of the preservative to be added is an amount of stablyexhibiting the efficacy for bacterial, molds, yeasts, or the like, andis preferably in a range of 0.01% by mass to 4% by mass with respect tothe total mass of the developer even though the amount thereof variesdepending on the type of bacteria, molds, and the yeasts. Further, it ispreferable that the preservative is used in combination of two or morekinds thereof so as to be effective for sterilizing various molds.

Examples of the chelate compound include ethylenediamine tetraaceticacid, a potassium salt thereof, and a sodium salt thereof;diethylenetriamine pentaacetic acid, a potassium salt thereof, and asodium salt thereof; triethylenetetraminehexaacetic acid, a potassiumsalt thereof, and a sodium salt thereof; hydroxyethylethylenediaminetriacetic acid, a potassium salt thereof, and a sodium salt thereof;nitrilotriacetic acid and a sodium salt thereof; and organic phosphonicacids such as 1-hydroxyethane-1,1-diphosphonic acid, a potassium saltthereof, and a sodium salt thereof; and aminotri(methylenephosphonicacid), a potassium salt, and a sodium salt thereof. A salt of an organicamine is effectively used in place of a sodium salt or a potassium saltof a chelating agent.

A chelating agent which is stably present in the composition of thetreatment liquid and does not disturb the printability is preferable asthe chelating agent. The content of the chelating agent is preferably ina range of 0.001% by mass to 1.0% by mass with respect to the total massof the developer.

As the antifoaming agent, a typical silicone-based self-emulsifying typecompound, an emulsifying type compound, a non-ionic compound having ahydrophilic-lipophilic balance (HLB) of 5 or less can be used. Asilicone antifoaming agent is preferable.

Further, a silicone-based surfactant is regarded as an antifoamingagent.

The content of the antifoaming agent is suitably in a range of 0.001% bymass to 1.0% by mass with respect to the total mass of the developer.

Examples of the organic acid include citric acid, acetic acid, oxalicacid, malonic acid, salicylic acid, caprylic acid, tartaric acid, malicacid, lactic acid, levulinic acid, p-toluenesulfonic acid,xylenesulfonic acid, phytic acid, and organic phosphonic acid. Theorganic acid can be used in the form of an alkali metal salt or ammoniumsalt thereof. The content of the organic acid is preferably in a rangeof 0.01% by mass to 0.5% by mass with respect to the total mass of thedeveloper.

Examples of the organic solvent include aliphatic hydrocarbons (hexane,heptane, “ISOPAR E, H, G” (manufactured by Exxon Chemical Japan Ltd.),and the like), aromatic hydrocarbons (toluene, xylene, and the like),halogenated hydrocarbon (methylene dichloride, ethylene dichloride,trichlene, monochlorobenzene, or the like), and a polar solvent.

Examples of the polar solvent include alcohols (such as methanol,ethanol, propanol, isopropanol, benzyl alcohol, ethylene glycolmonomethyl ether, 2-ethoxyethanol, diethylene glycol monoethyl ether,diethylene glycol monohexyl ether, triethylene glycol monomethyl ether,propylene glycol monoethyl ether, propylene glycol monomethyl ether,polyethylene glycol monomethyl ether, polypropylene glycol,tetraethylene glycol, ethylene glycol monobutyl ether, ethylene glycolmonobenzyl ether, ethylene glycol monophenyl ether, methyl phenylcarbinol, n-amyl alcohol, and methyl amyl alcohol), ketones (such asacetone, methyl ethyl ketone, ethyl butyl ketone, methyl isobutylketone, and cyclohexanone), esters (such as ethyl acetate, propylacetate, butyl acetate, amyl acetate, benzyl acetate, methyl lactate,butyl lactate, ethylene glycol monobutyl acetate, propylene glycolmonomethyl ether acetate, diethylene glycol acetate, diethyl phthalate,and butyl levulinate), and others (such as triethyl phosphate, tricresylphosphate, N-phenylethanolamine, and N-phenyldiethanolamine).

In a case where the organic solvent is insoluble in water, the organicsolvent can be used by being solubilized in water using a surfactant orthe like. In a case where the developer contains an organic solvent,from the viewpoints of safety and inflammability the concentration ofthe solvent in the developer is preferably less than 40% by mass.

Examples the inorganic acid and inorganic salt include phosphoric acid,methacrylic acid, primary ammonium phosphate, secondary ammoniumphosphate, primary sodium phosphate, secondary sodium phosphate, primarypotassium phosphate, secondary potassium phosphate, sodiumtripolyphosphate, potassium pyrophosphate, sodium hexametaphosphate,magnesium nitrate, sodium nitrate, potassium nitrate, ammonium nitrate,sodium sulfate, potassium sulfate, ammonium sulfate, sodium sulfite,ammonium sulfite, sodium hydrogensulfate, and nickel sulfate. Thecontent of the inorganic salt is preferably in a range of 0.01% by massto 0.5% by mass with respect to the total mass of the developer.

The developer is prepared by dissolving or dispersing each of theabove-described components in water as necessary. The concentration ofsolid contents in the developer is preferably in a range of 2% by massto 25% by mass. The developer can be used by preparing a concentrate anddiluting the concentrate with water at the time of use.

It is preferable that the developer is an aqueous developer.

From the viewpoint of the dispersibility of the development scum, it ispreferable that the developer contains an alcohol compound.

Examples of the alcohol compound include methanol, ethanol, propanol,isopropanol, and benzyl alcohol. Among these, benzyl alcohol ispreferable.

From the viewpoint of the dispersibility of the development scum, thecontent of the alcohol compound is preferably in a range of 0.01% bymass to 5% by mass, more preferably in a range of 0.1% by mass to 2% bymass, and particularly preferably in a range of 0.2% by mass to 1% bymass with respect to the total mass of the developer.

[Printing Step]

The printing method of using the lithographic printing plate obtainedaccording to the developer treatment system is not particularly limited,and the printing may be performed using a known method.

Examples thereof include a method of performing printing by supplyingink and dampening water as necessary to the lithographic printing plate.

The ink is not particularly limited, and known ink is used.

EXAMPLES

Hereinafter, the present disclosure will be described in detail withreference to examples, but the present disclosure is not limitedthereto. In the present examples, “%” and “part” respectively indicate“% by mass” and “part by mass” unless otherwise specified. Further, in apolymer compound, the molecular weight indicates the weight-averagemolecular weight (Mw) and the proportion of repeating constitutionalunits indicates mole percentage unless otherwise specified. Further, theweight-average molecular weight (Mw) is a value in terms of polystyreneobtained by performing measurement using gel permeation chromatography(GPC).

<Preparation of Supports 1 and 3 to 9>

As roughening treatments, the following (a) to (e) treatments wereperformed. Further, a washing treatment was performed between alltreatment steps.

(a) Alkali Etching Treatment

An aluminum plate (material JIS 1052) having a thickness of 0.3 mm wassubjected to an etching treatment by spraying an aqueous solution at atemperature of 60° C. in which the concentration of caustic soda was 25%by mass and the concentration of aluminum ions was 100 g/L using a spraytube. The etching amount of the surface of the aluminum plate to besubjected to an electrochemical roughening treatment was 3 g/m².

(b) Desmutting Treatment

Next, a desmutting treatment was performed by spraying a sulfuric acidaqueous solution (concentration of 300 g/L) at a temperature of 35° C.for 5 seconds from the spray tube.

(c) Electrolytic Roughening Treatment

Thereafter, an electrochemical roughening treatment was continuouslyperformed using an electrolytic solution (liquid temperature of 35° C.)obtained by dissolving aluminum chloride in a 1 mass % hydrochloric acidaqueous solution and adjusting the aluminum ion concentration to 4.5g/L, a 60 Hz AC power source, and a flat cell type electrolytic cell. Asine wave was used as the waveform of the AC power source. In theelectrochemical roughening treatment, the current density of thealuminum plate during the anodic reaction at the peak of the alternatingcurrent was 30 A/dm². The ratio between the total electric quantityduring the anodic reaction and the total electric quantity during thecathodic reaction of the aluminum plate was 0.95. The electric quantitywas set to 480 C/dm² in terms of the total electric quantity during theanodic reaction of the aluminum plate. The electrolytic solution wascirculated using a pump so that the stirring inside the electrolyticcell was performed.

(d) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying anaqueous solution at a temperature of 35° C. in which the concentrationof caustic soda was 5% by mass and the concentration of aluminum ionswas 5 g/L using a spray tube. The etching amount of the surface of thealuminum plate on which the electrolytic roughening treatment had beenperformed was 0.05 g/m².

(e) Desmutting Treatment

Next, a desmutting treatment was performed by spraying an aqueoussolution at a liquid temperature of 35° C. with a sulfuric acidconcentration of 300 g/L and an aluminum ion concentration of 5 g/L fromthe spray tube for 5 seconds.

The aluminum plate on which the roughening treatment had been performedwas subjected to an anodization treatment at a treatment temperature of38° C. and a current density of 15 A/dm² using a 22 mass % phosphoricacid aqueous solution as an electrolytic solution.

Thereafter, the aluminum plate was washed with water using a spray. Thefinal amount of the oxide film was 1.5 g/m². The surface of thesubstrate was imaged at a magnification of 150000 using an electronicmicroscope and the average pore diameter in a case of n=90 was actuallymeasured, and the value was 30 nm.

A support 1 is a support used after 10 days from the anodizationtreatment performed on the obtained support.

A support 3 is a support used after 1 day from the anodization treatmentperformed on the obtained support.

A support 4 is a support used after 3 days from the anodizationtreatment performed on the obtained support.

A support 5 is a support used after 1 day from the anodization treatmentperformed on the obtained support.

A support 6 is a support used after 7 days from the anodizationtreatment performed on the obtained support.

A support 7 is a support used after 1 day from the anodization treatmentperformed on the obtained support.

A support 8 is a support used after 1 year from the anodizationtreatment performed on the obtained support.

A support 9 is a support used after 1.5 years from the anodizationtreatment performed on the obtained support.

<Preparation of Support 2>

An aluminum alloy plate having a thickness of 0.3 mm and having acomposition listed in Table 1 was subjected to the following treatments(a) to (m), whereby a support 2 was prepared. Moreover, during alltreatment steps, a washing treatment was performed, and liquid cuttingwas performed using a nip roller after the washing treatment.

A support 2 is a support used after 10 days from the anodizationtreatment performed on the obtained support.

TABLE 1 Composition (% by mass) Si Fe Cu Mn Mg Zn Ti Al 0.085 0.3030.037 0 0 0 0.018 Remainder

(a) Mechanical Roughening Treatment (Brush Grain Method)

While supplying a suspension of pumice (specific gravity of 1.1 g/cm³)to the surface of an aluminum plate as a polishing slurry liquid, amechanical roughening treatment was performed using rotating bundlebristle brushes.

The mechanical roughening treatment was performed under conditions inwhich the median diameter of a polishing material pumice was 30 μm, thenumber of the bundle bristle brushes was four, and the rotation speed ofthe bundle bristle brushes was set to 250 rpm. The material of thebundle bristle brushes was nylon 6.10, the diameter of the brushbristles was 0.3 mm, and the bristle length was 50 mm. The bundlebristle brushes were produced by implanting bristles densely into theholes in a stainless steel cylinder having a diameter of 300 mm. Thedistance between two support rollers (with a diameter of 200 mm) of thelower portion of the bundle bristle brush was 300 mm. The bundle bristlebrushes were pressed until the load of a driving motor for rotating thebrushes became 10 kW plus with respect to the load before the bundlebristle brushes were pressed against the aluminum plate. The rotationdirection of the bundle bristle brushes was the same as the movingdirection of the aluminum plate.

(b) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 26% by mass and the concentration of aluminum ions was 6.5% by massusing a spray tube at a temperature of 70° C. Thereafter, washing withwater by spraying was performed. The amount of aluminum dissolved was 10g/m².

(c) Desmutting Treatment in Acidic Aqueous Solution

Next, a desmutting treatment was performed in a nitric acid aqueoussolution. As the nitric acid aqueous solution used in the desmuttingtreatment, a nitric acid electrolytic solution used in electrochemicalroughening of the subsequent step was used. The liquid temperature was35° C. The desmutting treatment was performed for 3 seconds by sprayingthe desmutting liquid using a spray.

(d) Electrochemical Roughening Treatment

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz. An electrolytic solution which had been adjustedto have a concentration of aluminum ions of 4.5 g/L by adding aluminumnitrate to a nitric acid aqueous solution having a concentration of 10.4g/L at a temperature of 35° C. was used. Using a trapezoidal rectangularwaveform AC having a time tp, until the current value reached a peakfrom zero, of 0.8 msec and the duty ratio of 1:1 as the AC power sourcewaveform, the electrochemical roughening treatment was performed using acarbon electrode as a counter electrode. As an auxiliary anode, ferritewas used. The current density was 30 A/dm² in terms of the peak currentvalue, and 5% of the current from the power source was separately flowedto the auxiliary anode. The electric quantity was 185 C/dm² as the totalelectric quantity at the time of anodization of the aluminum plate.Thereafter, washing with water by spraying was performed.

(e) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 5% by mass and the concentration of aluminum ions was 0.5% by massusing a spray tube at a temperature of 50° C. Thereafter, washing withwater by spraying was performed. The amount of aluminum dissolved was0.5 g/m².

(f) Desmutting Treatment in Acidic Aqueous Solution

Next, a desmutting treatment was performed in a sulfuric acid aqueoussolution. As the sulfuric acid aqueous solution used in the desmuttingtreatment, a solution in which the concentration of sulfuric acid was170 g/L and the concentration of aluminum ions was 5 g/L was used. Theliquid temperature was 60° C. The desmutting treatment was performed for3 seconds by spraying the desmutting liquid using a spray.

(g) Electrochemical Roughening Treatment

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz. An electrolytic solution which had been adjustedto have a concentration of aluminum ions of 4.5 g/L by adding aluminumchloride to an aqueous solution having a concentration hydrochloric acidof 6.2 g/L at a liquid temperature of 35° C. was used. Using atrapezoidal rectangular waveform AC having a time tp, until the currentvalue reached a peak from zero, of 0.8 msec and the duty ratio of 1:1,the electrochemical roughening treatment was performed using a carbonelectrode as a counter electrode. As an auxiliary anode, ferrite wasused. The current density was 25 A/dm² in terms of the peak currentvalue, and the electric quantity in the hydrochloric acid electrolysiswas 63 C/dm² as the total electric quantity at the time of anodizationof the aluminum plate. Thereafter, washing with water by spraying wasperformed.

(h) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 5% by mass and the concentration of aluminum ions was 0.5% by massusing a spray tube at a temperature of 50° C. Thereafter, washing withwater by spraying was performed. The amount of aluminum dissolved was0.1 g/m².

(i) Desmutting Treatment in Acidic Aqueous Solution

Next, a desmutting treatment was performed in a sulfuric acid aqueoussolution. The desmutting treatment was performed at a liquid temperatureof 35° C. for 4 seconds using the sulfuric acid aqueous solution(aluminum ions having a concentration of 5 g/L were contained in asulfuric acid aqueous solution having a concentration of 170 g/L) usedfor the anodization treatment step. The desmutting treatment wasperformed for 3 seconds by spraying the desmutting liquid using a spray.

(j) First Anodization Treatment

A first step of an anodization treatment was performed with an anodizingdevice using DC electrolysis. An anodized film having a predeterminedfilm thickness was formed by performing an anodization treatment underconditions listed in Table 2. An aqueous solution containing componentslisted in Table 2 was used as the electrolytic solution. In Tables 2 to4, the “component concentration” indicates the concentration (g/L) ofeach component described in the section of “liquid component”.

TABLE 2 First anodization treatment Component Tem- Current Film LiquidLiquid concentration perature density Time thickness type component(g/L) (° C.) (A/dm²) (s) (nm) Sulfuric H₂SO₄/Al 170/5 55 90 0.40 110acid

(k) Second Anodization Treatment

A second step of an anodization treatment was performed with ananodizing device using DC electrolysis. An anodized film having apredetermined film thickness was formed by performing an anodizationtreatment under conditions listed in Table 3. An aqueous solutioncontaining components listed in Table 3 was used as the electrolyticsolution.

TABLE 3 Second anodization treatment Component Tem- Current Film LiquidLiquid concentration perature density Time thickness type component(g/L) (° C.) (A/dm²) (s) (nm) Sulfuric H₂SO₄/Al 170/5 54 15 13 900 acid

(l) Third Anodization Treatment

A third step of an anodization treatment was performed with an anodizingdevice using DC electrolysis. An anodized film having a predeterminedfilm thickness was formed by performing an anodization treatment underconditions listed in Table 4. An aqueous solution containing componentslisted in Table 4 was used as the electrolytic solution.

TABLE 4 Third anodization treatment Component Tem- Current Film LiquidLiquid concentration perature density Time thickness type component(g/L) (° C.) (A/dm²) (s) (nm) Sulfuric H₂SO₄/Al 170/5 54 50 0.4 100 acid

(m) Hydrophilization Treatment

In order to ensure hydrophilicity of a non-image area, the non-imagearea was subjected to a silicate treatment by being dipped using 2.5% bymass of a No. 3 sodium silicate aqueous solution at 50° C. for 7seconds. The adhesion amount of Si was 8.5 mg/m². Thereafter, theresultant was washed with water using a spray.

The average diameter (average diameter of surface layer) oflarge-diameter pores on the surface of the anodized film havingmicropores obtained in the above-described manner, the average diameter(average diameter of bottom portion) of the large-diameter pores in acommunication position, the average diameter (diameter of small-diameterpores) of small-diameter pores in the communication position, theaverage depth of the large-diameter pores and the small-diameter pores,the thickness (thickness of barrier layer) of the anodized film from thebottom portion of the small-diameter pores to the surface of thealuminum plate, and the density of the small-diameter pores are listedin Tables 5 and 6. The small-diameter pores include first small-diameterpores and second small-diameter pores with depths different from eachother and small-diameter pores which are deeper than the other arereferred to as the first small-diameter pores.

TABLE 5 Micropores Large-diameter pores Average diameter of Averagediameter of Average depth/ Average depth/ surface layer bottom portionAverage depth Average diameter of Average diameter of (nm) (nm) (nm)surface layer bottom portion Shape 12 25 98 8.2 3.9 Inverted taper

TABLE 6 Micropores Small-diameter pores Average Ratio (average Densityof thickness Minimum Increase diameter of surface Average Averagecommunication of barrier thickness Density of magnificationlayer/diameter of diameter depth portion layer of barrier micropores ofsurface small-diameter (nm) (nm) (portions/μm²) (nm) layer (nm)(pores/μm²) area pores) 9.8 888, 968 800 17 16 500 4.0 1.22 (650)

In Table 6, the average value and the minimum value are shown as thebarrier layer thickness. The average value is obtained by measuring 50thicknesses of the anodized film from the bottom portion of the firstsmall-diameter pores to the surface of the aluminum plate andarithmetically averaging the values.

The average diameter of micropores (average diameter of thelarge-diameter pores and the small-diameter pores) is a value obtainedby observing 4 sheets (N=4) of the surfaces of the large-diameter poresand the surfaces of the small-diameter pores using a field emissionscanning electron microscope (FE-SEM) at a magnification of 150,000,measuring the diameters of micropores (the large-diameter pores and thesmall-diameter pores) present in a range of 400×600 nm² in the obtainedfour sheets of images, and averaging the values. Further, in a casewhere the depth of the large-diameter pores is deep and the diameter ofthe small-diameter pores is unlikely to be measured, the upper portionof the anodized film is cut and then various kinds of diameters areacquired.

The average depth of the large-diameter pores is a value obtained byobserving the cross section of the support (anodized film) using FE-TEMat a magnification of 500,000, measuring 60 cases (N=60) of distancesfrom the surface of an arbitrary micropore to the communication positionin the obtained image, and averaging the values. Further, the averagedepth of the small-diameter pores is a value obtained by observing thecross section of the support (anodized film) using FE-SEM (at amagnification of 50,000), measuring 25 cases of depths of arbitrarymicropores in the obtained image, and averaging the values.

The “density of the communication portion” indicates the density of thesmall-diameter pores of the cross section of the anodized film in thecommunication position. The “increase magnification of the surface area”indicates the value calculated based on the following Equation (A).

Increase magnification of surface area=1+pore density×((π×(averagediameter of surface layer/2+average diameter of bottomportion/2)×((average diameter of bottom portion/2−average diameter ofsurface layer/2)²+depth A ²)^(1/2)+π×(average diameter of bottomportion/2)²−π×(average diameter of surface layer/2)²))  Equation (A)

In the column of the “average depth (nm)” of the small-diameter pores,the average depth of the second small-diameter pores is shown on theleft side and the average depth of the first small-diameter pores isshown on the right side. In the column of the “density of communicationportion” of the small-diameter pores in Table E, the density of thefirst small-diameter pores is shown in the parentheses together with thedensity of the communication portion of the small-diameter pores.

In addition, the average diameter of the first small-diameter porespositioning from the bottom portion of the second small-diameter poresto the bottom portion of the first small-diameter pores wasapproximately 12 nm.

<Preparation of Support 10>

An aluminum plate having a thickness of 0.19 mm was immersed in a 40 g/Lsodium hydroxide aqueous solution at 60° C. for 8 seconds so as to bedegreased and then washed with demineralized water for 2 seconds. Next,the aluminum plate was subjected to an electrochemical rougheningtreatment in an aqueous solution containing 12 g/L of hydrochloric acidand 38 g/L of aluminum sulfate (18 hydrate) at a temperature of 33° C.and at a current density of 130 A/dm² using an AC for 15 seconds. Next,the aluminum plate was washed with demineralized water for 2 seconds,subjected to a desmutting treatment by being etched using 155 g/L of asulfuric acid aqueous solution at 70° C. for 4 seconds, and washed withdemineralized water at 25° C. for 2 seconds. The aluminum plate wassubjected to an anodization treatment in 155 g/L of a sulfuric acidaqueous solution for 13 seconds at a temperature of 45° C. and at acurrent density of 22 A/dm² and washed with demineralized water for 2seconds. Further, the aluminum plate was treated at 40° C. for 10seconds using 4 g/L of a polyvinyl phosphonic acid aqueous solution,washed with demineralized water at 20° C. for 2 seconds, and then dried,thereby preparing a support 10. The surface roughness Ra of the support10 was 0.21 μm and the amount of the anodized film was 4 g/m².

The support 10 is a support used after 10 days from the anodizationtreatment performed on the obtained support.

<Preparation of Supports 11 to 19>

An aluminum plate (aluminum alloy plate, material 1S) having a thicknessof 0.3 mm was subjected to any of the following treatments (A) to (I),thereby producing an aluminum support. Moreover, during all treatmentsteps, a washing treatment was performed, and liquid cutting wasperformed using a nip roller after the washing treatment.

[Treatment a (Supports 11 to 13)]

(A-a) Alkali Etching Treatment

An aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 26% by mass and the concentration of aluminum ions was 6.5% by massusing a spray at a temperature of 70° C. Thereafter, washing with waterby spraying was performed. The amount of aluminum to be dissolved in thesurface to be subsequently subjected to an electrochemical rougheningtreatment was 5 g/m².

(A-b) Desmutting Treatment Using Acidic Aqueous Solution

Next, a desmutting treatment was performed using an acidic aqueoussolution. Specifically, the desmutting treatment was performed byspraying the acidic aqueous solution to the aluminum plate for 3 secondsusing a spray. As the acidic aqueous solution used for the desmuttingtreatment, an aqueous solution having a sulfuric acid concentration of150 g/L was used. The liquid temperature was 30° C.

(A-c) Electrochemical Roughening Treatment Using Hydrochloric AcidAqueous Solution

Next, an electrochemical roughening treatment was performed using the ACcurrent and an electrolytic solution having a hydrochloric acidconcentration of 14 g/L, an aluminum ion concentration of 13 g/L, and asulfuric acid concentration of 3 g/L. The liquid temperature of theelectrolytic solution was 30° C. The aluminum ion concentration wasadjusted by adding aluminum chloride.

The waveform of the AC current was a sine wave in which the positive andnegative waveforms were symmetrical, the frequency was 50 Hz, the ratiobetween the anodic reaction time and the cathodic reaction time in onecycle of the AC current was 1:1, and the current density was 75 A/dm² interms of the peak current value of the AC current waveform. Further, thetotal electric quantity of the aluminum plate used for the anodicreaction was 450 C/dm², and the electrolytic treatment was performedfour times at energization intervals of 4 seconds for each of theelectric quantity of 112.5 C/dm². A carbon electrode was used as acounter electrode of the aluminum plate. Thereafter, a washing treatmentwas performed.

(A-d) Alkali Etching Treatment

The aluminum plate after being subjected to an electrochemicalroughening treatment was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 5% by mass and the concentration of aluminum ions was 0.5% by massusing a spray at a temperature of 45° C. Thereafter, washing with waterby spraying was performed. The amount of aluminum to be dissolved in thesurface after being subjected to an electrochemical roughening treatmentwas 0.2 g/m².

(A-e) Desmutting Treatment Using Acidic Aqueous Solution

Next, a desmutting treatment was performed using an acidic aqueoussolution. Specifically, the desmutting treatment was performed byspraying the acidic aqueous solution to the aluminum plate for 3 secondsusing a spray. As the acidic aqueous solution used for the desmuttingtreatment, a waste liquid generated in the anodization treatment step(an aqueous solution having a sulfuric acid concentration of 170 g/L andan aluminum ion concentration of 5 g/L) was used. The liquid temperaturewas 30° C.

(A-f) Anodization Treatment

An anodization treatment was performed with an anodizing device using DCelectrolysis illustrated in FIG. 5. An anodized film having apredetermined coating amount was formed by performing an anodizationtreatment under conditions in the columns of “first anodizationtreatment” listed in Table 7.

An aluminum plate 416 in an anodization treatment device 410 istransported as indicated by the arrow in FIG. 5. The aluminum plate 416is positively (+) charged by a power supply electrode 420 in a powersupply tank 412 in which an electrolytic solution 418 is stored.Further, the aluminum plate 416 is transported upward by a roller 422 inthe power supply tank 412, redirected downward by a nip roller 424,transported toward an electrolytic treatment tank 414 in which anelectrolytic solution 426 was stored, and redirected to the horizontaldirection by a roller 428. Next, the aluminum plate 416 is negatively(−) charged by an electrolytic electrode 430 so that an anodized film isformed on the surface thereof, and the aluminum plate 416 coming out ofthe electrolytic treatment tank 414 is transported to the next step. Inthe anodization treatment device 410, direction changing means is formedof the roller 422, the nip roller 424, and the roller 428. The aluminumplate 416 is transported in a mountain shape and an inverted U shape bythe roller 422, the nip roller 424, and the roller 428 in an inter-tankportion between the power supply tank 412 and the electrolytic treatmenttank 414. The power supply electrode 420 and the electrolytic electrode430 are connected to a DC power source 434.

(A-g) Pore Widening Treatment

The aluminum plate after being subjected to the anodization treatmentwas subjected to a pore widening treatment by being immersed in acaustic soda aqueous solution in which the concentration of caustic sodawas 5% by mass and the concentration of aluminum ions was 0.5% by massat a temperature listed in Table 7 under a time condition listed inTable 7. Thereafter, washing with water by spraying was performed.

[Treatment B (Support 14)]

(B-a) Alkali Etching Treatment

An aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 26% by mass and the concentration of aluminum ions was 6.5% by massusing a spray at a temperature of 70° C. Thereafter, washing with waterby spraying was performed. The amount of aluminum to be dissolved in thesurface to be subsequently subjected to an electrochemical rougheningtreatment was 5 g/m².

(B-b) Desmutting Treatment Using Acidic Aqueous Solution

Next, a desmutting treatment was performed using an acidic aqueoussolution. Specifically, the desmutting treatment was performed byspraying the acidic aqueous solution to the aluminum plate for 3 secondsusing a spray. As the acidic aqueous solution used for the desmuttingtreatment, an aqueous solution having a sulfuric acid concentration of150 g/L was used. The liquid temperature was 30° C.

(B-c) Electrochemical Roughening Treatment Using Hydrochloric AcidAqueous Solution.

Next, an electrochemical roughening treatment was performed using the ACcurrent and an electrolytic solution having a hydrochloric acidconcentration of 14 g/L, an aluminum ion concentration of 13 g/L, and asulfuric acid concentration of 3 g/L. The liquid temperature of theelectrolytic solution was 30° C. The aluminum ion concentration wasadjusted by adding aluminum chloride.

The waveform of the AC current was a sine wave in which the positive andnegative waveforms were symmetrical, the frequency was 50 Hz, the ratiobetween the anodic reaction time and the cathodic reaction time in onecycle of the AC current was 1:1, and the current density was 75 A/dm² interms of the peak current value of the AC current waveform. Further, thetotal electric quantity of the aluminum plate used for the anodicreaction was 450 C/dm², and the electrolytic treatment was performedfour times at energization intervals of 4 seconds for each of theelectric quantity of 112.5 C/dm². A carbon electrode was used as acounter electrode of the aluminum plate. Thereafter, a washing treatmentwas performed.

(B-d) Alkali Etching Treatment

The aluminum plate after being subjected to an electrochemicalroughening treatment was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 5% by mass and the concentration of aluminum ions was 0.5% by massusing a spray at a temperature of 45° C. Thereafter, washing with waterby spraying was performed. The amount of aluminum to be dissolved in thesurface after being subjected to an electrochemical roughening treatmentwas 0.2 g/m².

(B-e) Desmutting Treatment Using Acidic Aqueous Solution

Next, a desmutting treatment was performed using an acidic aqueoussolution. Specifically, the desmutting treatment was performed byspraying the acidic aqueous solution to the aluminum plate for 3 secondsusing a spray. As the acidic aqueous solution used for the desmuttingtreatment, a waste liquid generated in the anodization treatment step(an aqueous solution having a sulfuric acid concentration of 170 g/L andan aluminum ion concentration of 5 g/L) was used. The liquid temperaturewas 30° C.

(B-f) First Stage Anodization Treatment

A first stage anodization treatment was performed with an anodizingdevice using DC electrolysis and having a structure illustrated in FIG.5. An anodized film having a predetermined coating amount was formed byperforming an anodization treatment under conditions in the columns of“first anodization treatment” listed in Table 7.

(B-g) Pore Widening Treatment

The aluminum plate after being subjected to the anodization treatmentwas subjected to a pore widening treatment by being immersed in acaustic soda aqueous solution in which the concentration of caustic sodawas 5% by mass and the concentration of aluminum ions was 0.5% by massat a temperature of 40° C. under a time condition listed in Table 7.Thereafter, washing with water by spraying was performed.

(B-h) Second Stage Anodization Treatment

A second stage anodization treatment was performed with an anodizingdevice using DC electrolysis and having a structure illustrated in FIG.5. An anodized film having a predetermined coating amount was formed byperforming an anodization treatment under conditions in the columns of“second anodization treatment” listed in Table 7.

[Treatment D (Support 15)]

(D-a) Mechanical Roughening Treatment (Brush Grain Method)

While supplying a suspension of pumice (specific gravity of 1.1 g/cm³)to the surface of an aluminum plate as a polishing slurry liquid using adevice illustrated in FIG. 6, a mechanical roughening treatment wasperformed using rotating bundle bristle brushes. In FIG. 6, thereference numeral 1 represents an aluminum plate, the reference numerals2 and 4 represent roller-like brushes (in the present examples, bundlebristle brushes), the reference numeral 3 represents a polishing slurryliquid, and the reference numerals 5, 6, 7, and 8 represent a supportroller.

The mechanical roughening treatment is performed under conditions inwhich the median diameter (μm) of a polishing material was 30 μm, thenumber of the brushes was four, and the rotation speed (rpm) of thebrushes was set to 250 rpm. The material of the bundle bristle brusheswas nylon 6.10, the diameter of the brush bristles was 0.3 mm, and thebristle length was 50 mm. The brushes were produced by implantingbristles densely into the holes in a stainless steel cylinder having adiameter of 300 mm. The distance between two support rollers (a diameterof 200 mm) of the lower portion of the bundle bristle brush was 300 mm.The bundle bristle brushes were pressed until the load of a drivingmotor for rotating the brushes became 10 kW plus with respect to theload before the bundle bristle brushes were pressed against the aluminumplate. The rotation direction of the brushes was the same as the movingdirection of the aluminum plate.

(D-b) Alkali Etching Treatment

An aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 26% by mass and the concentration of aluminum ions was 6.5% by massusing a spray at a temperature of 70° C. Thereafter, washing with waterby spraying was performed. The amount of aluminum to be dissolved in thesurface to be subsequently subjected to an electrochemical rougheningtreatment was 10 g/m².

(D-c) Desmutting Treatment Using Acidic Aqueous Solution

Next, a desmutting treatment was performed using an acidic aqueoussolution. Specifically, the desmutting treatment was performed byspraying the acidic aqueous solution to the aluminum plate for 3 secondsusing a spray. As the acidic aqueous solution used for the desmuttingtreatment, a waste liquid of nitric acid used for the subsequentelectrochemical roughening treatment step was used. The liquidtemperature was 35° C.

(D-d) Electrochemical Roughening Treatment Using Nitric Acid AqueousSolution

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz in nitric acid electrolysis. As an electrolyticsolution at this time, an electrolytic solution which had been adjustedto have a concentration of aluminum ions of 4.5 g/L by adding aluminumnitrate to a nitric acid aqueous solution having a concentration of 10.4g/L at a liquid temperature of 35° C. was used. The AC power sourcewaveform is a waveform illustrated in FIG. 3. Further, using atrapezoidal rectangular waveform AC having a time tp, until the currentvalue reached a peak from zero, of 0.8 msec and the duty ratio of 1:1 asthe AC power source waveform, the electrochemical roughening treatmentwas performed using a carbon electrode as a counter electrode. As anauxiliary anode, ferrite was used. An electrolytic cell illustrated inFIG. 5 was used as the electrolytic cell. The current density was 30A/dm² in terms of the peak current value, and 5% of the current from thepower source was separately flowed to the auxiliary anode. The electricquantity (C/dm²) was 185 C/dm² as the total electric quantity at thetime of anodization of the aluminum plate.

(D-e) Alkali Etching Treatment

The aluminum plate obtained in the above-described manner was subjectedto an etching treatment by spraying a caustic soda aqueous solution inwhich the concentration of caustic soda was 27% by mass and theconcentration of aluminum ions was 2.5% by mass using a spray tube at atemperature of 50° C. Thereafter, washing with water by spraying wasperformed. The amount of aluminum dissolved was 3.5 g/m².

(D-f) Desmutting Treatment in Acidic Aqueous Solution

Next, a desmutting treatment was performed in a sulfuric acid aqueoussolution. Specifically, the desmutting treatment was performed byspraying the sulfuric acid aqueous solution to the aluminum plate for 3seconds using a spray. As the sulfuric acid aqueous solution used forthe desmutting treatment, an aqueous solution having a sulfuric acidconcentration of 170 g/L and an aluminum ion concentration of 5 g/L wasused. The liquid temperature was 30° C.

(D-g) Electrochemical Roughening Treatment Using Hydrochloric AcidAqueous Solution

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz in hydrochloric acid electrolysis. As anelectrolytic solution, an electrolytic solution which had been adjustedto have a concentration of aluminum ions of 4.5 g/L by adding aluminumchloride to an aqueous solution having 6.2 g/L of hydrochloric acid at aliquid temperature of 35° C. was used. The AC power source waveform is awaveform illustrated in FIG. 3. Further, using a trapezoidal rectangularwaveform AC having a time tp, until the current value reached a peakfrom zero, of 0.8 msec and the duty ratio of 1:1 as the AC power sourcewaveform, the electrochemical roughening treatment was performed using acarbon electrode as a counter electrode. As an auxiliary anode, ferritewas used. An electrolytic cell illustrated in FIG. 5 was used as theelectrolytic cell. The current density was 25 A/dm² in terms of the peakcurrent value, and the electric quantity (C/dm²) in the hydrochloricacid electrolysis was 63 C/dm² as the total electric quantity at thetime of anodization of the aluminum plate. Thereafter, washing withwater was performed using a spray.

(D-h) Alkali Etching Treatment

The aluminum plate obtained in the above-described manner was subjectedto an etching treatment by spraying a caustic soda aqueous solution inwhich the concentration of caustic soda was 5% by mass and theconcentration of aluminum ions was 0.5% by mass using a spray at atemperature of 60° C. Thereafter, washing with water by spraying wasperformed. The amount of aluminum to be dissolved was 0.2 g/m².

(D-i) Desmutting Treatment Using Acidic Aqueous Solution

Next, a desmutting treatment was performed using a sulfuric acid aqueoussolution. Specifically, the desmutting treatment was performed byspraying the sulfuric acid aqueous solution to the aluminum plate for 4seconds using a spray. As the sulfuric acid aqueous solution used forthe desmutting treatment, a waste liquid generated in the anodizationtreatment step (an aqueous solution having a sulfuric acid concentrationof 170 g/L and an aluminum ion concentration of 5 g/L) was used. Theliquid temperature was 35° C.

(D-j) Anodization Treatment

An anodization treatment was performed with an anodizing device using DCelectrolysis and having a structure illustrated in FIG. 5. An anodizedfilm having a predetermined coating amount was formed by performing ananodization treatment under conditions in the columns of “firstanodization treatment” listed in Table 7.

(D-k) Pore Widening Treatment

The aluminum plate after being subjected to the anodization treatmentwas subjected to a pore widening treatment by being immersed in acaustic soda aqueous solution in which the concentration of caustic sodawas 5% by mass and the concentration of aluminum ions was 0.5% by massat a temperature of 40° C. for 3 seconds. Thereafter, washing with waterby spraying was performed.

(D-l) Hydrophilization Treatment

In order to ensure hydrophilicity of a non-image area, a silicatetreatment was performed by dipping the aluminum plate obtained using2.5% by mass of a No. 3 sodium silicate aqueous solution at 50° C. for 7seconds. The adhesion amount of Si was 8.5 mg/m². Thereafter, theresultant was washed with water using a spray.

The average diameter of micropores is calculated by observing 4 sheets(N=4) of the surfaces of the anodized film using FE-SEM at amagnification of 150000, measuring the diameters of micropores presentin a range of 400 nm×600 nm in the obtained four sheets of images, andaveraging the values.

Further, in a case where the shape of the micropores is not circular, anequivalent circle diameter is used. The “equivalent circle diameter” isa diameter of a circle obtained by assuming the shape of an openingportion of a micropore as a circle having the same projected area as theprojected area of the opening portion.

[Treatment F (Support 16)]

(F-a) Alkali Etching Treatment

An aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 26% by mass and the concentration of aluminum ions was 6.5% by massusing a spray at a temperature of 70° C. Thereafter, washing with waterby spraying was performed. The amount of aluminum to be dissolved in thesurface to be subsequently subjected to an electrochemical rougheningtreatment was 5 g/m².

(F-b) Desmutting Treatment Using Acidic Aqueous Solution

Next, a desmutting treatment was performed using an acidic aqueoussolution. Specifically, the desmutting treatment was performed byspraying the acidic aqueous solution to the aluminum plate for 3 secondsusing a spray. As the acidic aqueous solution used for the desmuttingtreatment, an aqueous solution having 150 g/L of sulfuric acid was used.The liquid temperature was 30° C.

(F-c) Electrochemical Roughening Treatment

Next, an electrochemical roughening treatment was performed using the ACcurrent and an electrolytic solution having a hydrochloric acidconcentration of 14 g/L, an aluminum ion concentration of 13 g/L, and asulfuric acid concentration of 3 g/L. The liquid temperature of theelectrolytic solution was 30° C. The aluminum ion concentration wasadjusted by adding aluminum chloride.

The waveform of the AC current was a sine wave in which the positive andnegative waveforms were symmetrical, the frequency was 50 Hz, the ratiobetween the anodic reaction time and the cathodic reaction time in onecycle of the AC current was 1:1, and the current density was 75 A/dm² interms of the peak current value of the AC current waveform. Further, thetotal electric quantity of the aluminum plate used for the anodicreaction was 450 C/dm², and the electrolytic treatment was performedfour times at energization intervals of 4 seconds for each of theelectric quantity of 112.5 C/dm². A carbon electrode was used as acounter electrode of the aluminum plate. Thereafter, a washing treatmentwas performed.

(F-d) Alkali Etching Treatment

The aluminum plate after being subjected to an electrochemicalroughening treatment was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 5% by mass and the concentration of aluminum ions was 0.5% by massusing a spray at a temperature of 45° C. The amount of aluminum to bedissolved in the surface after being subjected to an electrochemicalroughening treatment was 0.2 g/m². Thereafter, a washing treatment wasperformed.

(F-e) Desmutting Treatment Using Acidic Aqueous Solution

Next, a desmutting treatment was performed using an acidic aqueoussolution. Specifically, the desmutting treatment was performed byspraying the acidic aqueous solution to the aluminum plate for 3 secondsusing a spray. As the acidic aqueous solution used for the desmuttingtreatment, an aqueous solution having a sulfuric acid concentration of170 g/L and an aluminum ion concentration of 5 g/L was used. The liquidtemperature was 35° C.

(F-f) First Stage Anodization Treatment

A first stage anodization treatment was performed with an anodizingdevice using DC electrolysis and having a structure illustrated in FIG.5. An anodized film having a predetermined coating amount was formed byperforming an anodization treatment under conditions in the columns of“first anodization treatment” listed in Table 7.

(F-g) Second Stage Anodization Treatment

A second stage anodization treatment was performed with an anodizingdevice using DC electrolysis and having a structure illustrated in FIG.5. An anodized film having a predetermined coating amount was formed byperforming an anodization treatment under conditions in the columns of“second anodization treatment” listed in Table 7.

[Treatment G (Support 17)]

(G-a) Alkali Etching Treatment

An aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 26% by mass and the concentration of aluminum ions was 6.5% by massusing a spray at a temperature of 70° C. Thereafter, washing with waterby spraying was performed. The amount of aluminum to be dissolved in thesurface to be subsequently subjected to an electrochemical rougheningtreatment was 5 g/m².

(G-b) Desmutting Treatment Using Acidic Aqueous Solution

Next, a desmutting treatment was performed using an acidic aqueoussolution. Specifically, the desmutting treatment was performed byspraying the acidic aqueous solution to the aluminum plate for 3 secondsusing a spray. As the acidic aqueous solution used for the desmuttingtreatment, an aqueous solution having 150 g/L of sulfuric acid was used.The liquid temperature was 30° C.

(G-c) Electrochemical Roughening Treatment

Next, an electrochemical roughening treatment was performed using the ACcurrent and an electrolytic solution having a hydrochloric acidconcentration of 14 g/L, an aluminum ion concentration of 13 g/L, and asulfuric acid concentration of 3 g/L. The liquid temperature of theelectrolytic solution was 30° C. The aluminum ion concentration wasadjusted by adding aluminum chloride.

The waveform of the AC current was a sine wave in which the positive andnegative waveforms were symmetrical, the frequency was 50 Hz, the ratiobetween the anodic reaction time and the cathodic reaction time in onecycle of the AC current was 1:1, and the current density was 75 A/dm² interms of the peak current value of the AC current waveform. Further, thetotal electric quantity of the aluminum plate used for the anodicreaction was 450 C/dm², and the electrolytic treatment was performedfour times at energization intervals of 4 seconds for each of theelectric quantity of 112.5 C/dm². A carbon electrode was used as acounter electrode of the aluminum plate. Thereafter, a washing treatmentwas performed.

(G-d) Alkali Etching Treatment

The aluminum plate after being subjected to an electrochemicalroughening treatment was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 5% by mass and the concentration of aluminum ions was 0.5% by massusing a spray at a temperature of 45° C. The amount of aluminum to bedissolved in the surface after being subjected to an electrochemicalroughening treatment was 0.2 g/m². Thereafter, a washing treatment wasperformed.

(G-e) Desmutting Treatment Using Acidic Aqueous Solution

Next, a desmutting treatment was performed using an acidic aqueoussolution. Specifically, the desmutting treatment was performed byspraying the acidic aqueous solution to the aluminum plate for 3 secondsusing a spray. As the acidic aqueous solution used for the desmuttingtreatment, an aqueous solution having a sulfuric acid concentration of170 g/L and an aluminum ion concentration of 5 g/L was used. The liquidtemperature was 35° C.

(G-f) First Stage Anodization Treatment

A first stage anodization treatment was performed with an anodizingdevice using DC electrolysis and having a structure illustrated in FIG.5. An anodized film having a predetermined coating amount was formed byperforming an anodization treatment under conditions in the columns of“first anodization treatment” listed in Table 7.

(G-g) Pore Widening Treatment

The aluminum plate after being subjected to the anodization treatmentwas subjected to a pore widening treatment by being immersed in acaustic soda aqueous solution in which the concentration of caustic sodawas 5% by mass and the concentration of aluminum ions was 0.5% by massat a temperature of 40° C. under a time condition listed in Table 7.Thereafter, washing with water by spraying was performed.

(G-h) Second Stage Anodization Treatment

A second stage anodization treatment was performed with an anodizingdevice using DC electrolysis and having a structure illustrated in FIG.5. An anodized film having a predetermined coating amount was formed byperforming an anodization treatment under conditions in the columns of“second anodization treatment” listed in Table 7.

[Treatment H (Support 18)]

(H-a) Alkali Etching Treatment

An aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 26% by mass and the concentration of aluminum ions was 6.5% by massusing a spray at a temperature of 70° C. Thereafter, washing with waterby spraying was performed. The amount of aluminum to be dissolved in thesurface to be subsequently subjected to an electrochemical rougheningtreatment was 5 g/m².

(H-b) Desmutting Treatment Using Acidic Aqueous Solution

Next, a desmutting treatment was performed using an acidic aqueoussolution. Specifically, the desmutting treatment was performed byspraying the acidic aqueous solution to the aluminum plate for 3 secondsusing a spray. As the acidic aqueous solution used for the desmuttingtreatment, an aqueous solution having 150 g/L of sulfuric acid was used.The liquid temperature was 30° C.

(H-c) Electrochemical Roughening Treatment

Next, an electrochemical roughening treatment was performed using the ACcurrent and an electrolytic solution having a hydrochloric acidconcentration of 14 g/L, an aluminum ion concentration of 13 g/L, and asulfuric acid concentration of 3 g/L. The liquid temperature of theelectrolytic solution was 30° C. The aluminum ion concentration wasadjusted by adding aluminum chloride.

The waveform of the AC current was a sine wave in which the positive andnegative waveforms were symmetrical, the frequency was 50 Hz, the ratiobetween the anodic reaction time and the cathodic reaction time in onecycle of the AC current was 1:1, and the current density was 75 A/dm² interms of the peak current value of the AC current waveform. Further, thetotal electric quantity of the aluminum plate used for the anodicreaction was 450 C/dm², and the electrolytic treatment was performedfour times at energization intervals of 4 seconds for each of theelectric quantity of 112.5 C/dm². A carbon electrode was used as acounter electrode of the aluminum plate. Thereafter, a washing treatmentwas performed.

(H-d) Alkali Etching Treatment

The aluminum plate after being subjected to an electrochemicalroughening treatment was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 5% by mass and the concentration of aluminum ions was 0.5% by massusing a spray at a temperature of 45° C. The amount of aluminum to bedissolved in the surface after being subjected to an electrochemicalroughening treatment was 0.2 g/m². Thereafter, a washing treatment wasperformed.

(H-e) Desmutting Treatment Using Acidic Aqueous Solution

Next, a desmutting treatment was performed using an acidic aqueoussolution. Specifically, the desmutting treatment was performed byspraying the acidic aqueous solution to the aluminum plate for 3 secondsusing a spray. As the acidic aqueous solution used for the desmuttingtreatment, an aqueous solution having a sulfuric acid concentration of170 g/L and an aluminum ion concentration of 5 g/L was used. The liquidtemperature was 35° C.

(H-f) First Stage Anodization Treatment

A first stage anodization treatment was performed with an anodizingdevice using DC electrolysis and having a structure illustrated in FIG.5. An anodized film having a predetermined coating amount was formed byperforming an anodization treatment under conditions in the columns of“first anodization treatment” listed in Table 7.

(H-g) Second Stage Anodization Treatment

A second stage anodization treatment was performed with an anodizingdevice using DC electrolysis and having a structure illustrated in FIG.5. An anodized film having a predetermined coating amount was formed byperforming an anodization treatment under conditions in the columns of“second anodization treatment” listed in Table 7.

[Treatment I (Support 19)]

(I-a) Alkali Etching Treatment

An aluminum plate was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 26% by mass and the concentration of aluminum ions was 6.5% by massusing a spray at a temperature of 70° C. Thereafter, washing with waterby spraying was performed. The amount of aluminum to be dissolved in thesurface to be subsequently subjected to an electrochemical rougheningtreatment was 5 g/m².

(I-b) Desmutting Treatment Using Acidic Aqueous Solution

Next, a desmutting treatment was performed using an acidic aqueoussolution. Specifically, the desmutting treatment was performed byspraying the acidic aqueous solution to the aluminum plate for 3 secondsusing a spray. As the acidic aqueous solution used for the desmuttingtreatment, an aqueous solution having 150 g/L of sulfuric acid was used.The liquid temperature was 30° C.

(I-c) Electrochemical Roughening Treatment

Next, an electrochemical roughening treatment was performed using the ACcurrent and an electrolytic solution having a hydrochloric acidconcentration of 14 g/L, an aluminum ion concentration of 13 g/L, and asulfuric acid concentration of 3 g/L. The liquid temperature of theelectrolytic solution was 30° C. The aluminum ion concentration wasadjusted by adding aluminum chloride.

The waveform of the AC current was a sine wave in which the positive andnegative waveforms were symmetrical, the frequency was 50 Hz, the ratiobetween the anodic reaction time and the cathodic reaction time in onecycle of the AC current was 1:1, and the current density was 75 A/dm² interms of the peak current value of the AC current waveform. Further, thetotal electric quantity of the aluminum plate used for the anodicreaction was 450 C/dm², and the electrolytic treatment was performedfour times at energization intervals of 4 seconds for each of theelectric quantity of 112.5 C/dm². A carbon electrode was used as acounter electrode of the aluminum plate. Thereafter, a washing treatmentwas performed.

(I-d) Alkali Etching Treatment

The aluminum plate after being subjected to an electrochemicalroughening treatment was subjected to an etching treatment by spraying acaustic soda aqueous solution in which the concentration of caustic sodawas 5% by mass and the concentration of aluminum ions was 0.5% by massusing a spray at a temperature of 45° C. The amount of aluminum to bedissolved in the surface after being subjected to an electrochemicalroughening treatment was 0.2 g/m². Thereafter, a washing treatment wasperformed.

(I-e) Desmutting Treatment Using Acidic Aqueous Solution

Next, a desmutting treatment was performed using an acidic aqueoussolution. Specifically, the desmutting treatment was performed byspraying the acidic aqueous solution to the aluminum plate for 3 secondsusing a spray. As the acidic aqueous solution used for the desmuttingtreatment, an aqueous solution having a sulfuric acid concentration of170 g/L and an aluminum ion concentration of 5 g/L was used. The liquidtemperature was 35° C.

(I-f) First Stage Anodization Treatment

A first stage anodization treatment was performed with an anodizingdevice using DC electrolysis and having a structure illustrated in FIG.5. An anodized film having a predetermined coating amount was formed byperforming an anodization treatment under conditions in the columns of“first anodization treatment” listed in Table 7.

(I-g) Pore Widening Treatment

The aluminum plate after being subjected to the anodization treatmentwas subjected to a pore widening treatment by being immersed in acaustic soda aqueous solution in which the concentration of caustic sodawas 5% by mass and the concentration of aluminum ions was 0.5% by massat a temperature of 40° C. under a time condition listed in Table 7.Thereafter, washing with water by spraying was performed.

(I-h) Second Stage Anodization Treatment

A second stage anodization treatment was performed with an anodizingdevice using DC electrolysis and having a structure illustrated in FIG.5. An anodized film having a predetermined coating amount was formed byperforming an anodization treatment under conditions in the columns of“second anodization treatment” listed in Table 7.

<Preparation of Support 20>

[Aluminum Plate]

A molten metal was prepared using an aluminum alloy containing 0.06% bymass of Si, 0.30% by mass of Fe, 0.005% by mass of Cu, 0.001% by mass ofMn, 0.001% by mass of Mg, 0.001% by mass of Zn, and 0.03% by mass of Tiand, as the remainder, aluminum and unavoidable impurities, a moltenmetal treatment and filtration were performed, and an ingot having athickness of 500 mm and a width of 1200 mm was prepared according to aDC casting method. The surface was scraped off using a surface grinderhaving an average thickness of 10 mm and heated at 550° C. andmaintained the state for approximately 5 hours. After the temperaturewas decreased to 400° C., a rolled sheet having a thickness of 2.7 mmwas obtained using a hot rolling mill. Further, a heat treatment wasperformed thereon at 500° C. using a continuous annealing machine, and acold rolling was performed so that the thickness of the rolled sheet wasfinished to 0.24 mm, thereby obtaining an aluminum plate formed of JIS1050 material. The following surface treatment was performed after thewidth of this aluminum plate was adjusted to 1030 mm.

[Surface Treatment]

The surface treatment was performed by continuously performing thefollowing treatments of (b) to (j).

Further, liquid cutting was performed using a nip roller after eachtreatment and washing with water.

(b) Alkali Etching Treatment

The aluminum plate obtained in the above-described manner was subjectedto an etching treatment by spraying an aqueous solution in which theconcentration of caustic soda was 2.6% by mass and the concentration ofaluminum ions was 6.5% by mass at a temperature of 70° C. so that 6 g/m²of the aluminum plate was dissolved. Thereafter, washing with water byspraying was performed.

(c) Desmutting Treatment

A desmutting treatment was performed by spraying an acidic aqueoussolution (containing 0.5% by mass of aluminum ions) having a nitric acidconcentration of 1% by mass at a temperature of 30° C. Thereafter,washing with water was performed using a spray. As the nitric acidaqueous solution used for the desmutting treatment, a waste liquid usedfor the step of performing the electrochemical roughening treatmentusing the alternating current in a nitric acid aqueous solution wasused.

(d) Electrochemical Roughening Treatment

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz. As an electrolytic solution at this time, anaqueous solution containing 10.5 g/L of nitric acid (containing 5 g/L ofaluminum ions and 0.007% by mass of ammonium ions) at a liquidtemperature of 50° C. was used. The AC power source waveform is awaveform illustrated in FIG. 3. Further, using a trapezoidal rectangularwaveform AC having a time tp, until the current value reached a peakfrom zero, of 0.8 msec and the duty ratio of 1:1 as the AC power sourcewaveform, the electrochemical roughening treatment was performed using acarbon electrode as a counter electrode. As an auxiliary anode, ferritewas used. An electrolytic cell illustrated in FIG. 5 was used as theelectrolytic cell. The current density was 30 A/dm² in terms of the peakcurrent value, and the electric quantity was 220 C/dm² as the totalelectric quantity at the time of anodization of the aluminum plate.Further, 5% of the current from the power source was separately flowedto the auxiliary anode. Thereafter, washing with water was performedusing a spray.

(e) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying anaqueous solution in which the concentration of caustic soda was 26% bymass and the concentration of aluminum ions was 6.5% by mass at atemperature of 32° C. so that 0.25 g/m² of the aluminum plate wasdissolved. Further, a smut component mainly containing aluminumhydroxide generated at the time of the electrochemical rougheningtreatment using the alternating current at the former stage was removed,an edge portion of a generated pit was dissolved to smooth the edgeportion. Thereafter, washing with water by spraying was performed.

(f) Desmutting Treatment

A desmutting treatment was performed by spraying an acidic aqueoussolution (containing 4.5% by mass of aluminum ions) having a sulfuricacid concentration of 15% by mass at a temperature of 30° C. Thereafter,washing with water was performed using a spray. As the nitric acidaqueous solution used for the desmutting treatment, a waste liquid usedfor the step of performing the electrochemical roughening treatmentusing the alternating current in a nitric acid aqueous solution wasused.

(g) Electrochemical Roughening Treatment

An electrochemical roughening treatment was continuously performed usingan AC voltage of 60 Hz. As an electrolytic solution at this time, anaqueous solution containing 2.5 g/L of hydrochloric acid (containing 5g/L of aluminum ions) at a liquid temperature of 35° C. was used. The ACpower source waveform is a waveform illustrated in FIG. 3. Further,using a trapezoidal rectangular waveform AC having a time tp, until thecurrent value reached a peak from zero, of 0.8 msec and the duty ratioof 1:1 as the AC power source waveform, the electrochemical rougheningtreatment was performed using a carbon electrode as a counter electrode.As an auxiliary anode, ferrite was used. An electrolytic cellillustrated in FIG. 5 was used as the electrolytic cell. The currentdensity was 25 A/dm² in terms of the peak current value, and theelectric quantity was 50 C/dm² as the total electric quantity at thetime of anodization of the aluminum plate. Thereafter, washing withwater was performed using a spray.

(h) Alkali Etching Treatment

The aluminum plate was subjected to an etching treatment by spraying anaqueous solution in which the concentration of caustic soda was 26% bymass and the concentration of aluminum ions was 6.5% by mass at atemperature of 32° C. so that 0.1 g/m² of the aluminum plate wasdissolved. Further, a smut component mainly containing aluminumhydroxide generated at the time of the electrochemical rougheningtreatment using the alternating current at the former stage was removed,an edge portion of a generated pit was dissolved to smooth the edgeportion. Thereafter, washing with water by spraying was performed.

(i) Desmutting Treatment

A desmutting treatment was performed by spraying an acidic aqueoussolution (containing 0.5% by mass of aluminum ions) having a sulfuricacid concentration of 25% by mass at a temperature of 60° C. Thereafter,washing with water was performed using a spray.

(j) Anodization Treatment

An anodization treatment was performed with an anodizing device having astructure illustrated in FIG. 5, thereby obtaining a support 20. As theelectrolytic solution supplied to first and second electrolysisportions, sulfuric acid was used. The electrolytic solution had asulfuric acid concentration of 170 g/L (containing 0.5% by mass ofaluminum ions) and the temperature thereof was 38° C. Thereafter,washing with water was performed using a spray. The final oxide coatingamount was 2.7 g/m².

The supports 11 to 20 are supports used after 10 days from theanodization treatment performed on the obtained supports.

TABLE 7 First anodization treatment Sulfuric Phosphoric acid acid con-con- Roughening treatment centration centration Hydrochloric of ofElapsed Alkali Nitric acid Alkali acid Alkali electrolytic electrolyticTem- time of etching electrolysis etching electrolysis etching solutionsolution perature Support support Brush grain (g/m²) (C/dm²) (g/m²)(C/dm²) (g/m²) (g/l) (g/l) (° C.) Support 1 10 days — 3 — — 480 0.05 —220 38 Support 2 10 days Available 10 185 0.5 63 0.1 170 — 55 Support 31 day — 3 — — 480 0.05 — 220 38 Support 4 3 days — 3 — — 480 0.05 — 22038 Support 5 1 hour — 3 — — 480 0.05 — 220 38 Support 6 7 days — 3 — —480 0.05 — 220 38 Support 7 1 month — 3 — — 480 0.05 — 220 38 Support 81 year — 3 — — 480 0.05 — 220 38 Support 9 1.5 years — 3 — — 480 0.05 —220 38 Support 10 10 days — — — — 130 — 155 — 45 Support 11 10 days — 5— — 450 0.2 170 — 50 Support 12 10 days — 5 — — 450 0.2 170 — 50 Support13 10 days — 5 — — 450 0.2 170 — 15 Support 14 10 days — 5 — — 450 0.2170 — 50 Support 15 10 days Available 10 185 3.5 63 0.2 170 — 50 Support16 10 days — 5 — — 450 0.2 — 150 35 Support 17 10 days — 5 — — 450 0.2 —150 35 Support 18 10 days — 5 — — 450 0.2 — 150 35 Support 19 10 days —5 — — 450 0.2 — 150 35 Support 20 10 days — 6 220 0.25 50 0.1 170 — 38Second anodization treatment Phosphoric Sulfuric acid acid Firstanodization Pore widening concentration concentration treatmenttreatment of of Current Coating Tem- electrolytic electrolytic Tem-Current Coating density amount perature Time solution solution peraturedensity amount Support (A/dm²) (g/m²) (° C.) (second) (g/l) (g/l) (° C.)(A/dm²) (g/m²) Support 1 15 1.5 — — — — — — — Support 2 90 0.3 — — 170 —54 15 2.4 Support 3 15 1.5 — — — — — — — Support 4 15 1.5 — — — — — — —Support 5 15 1.5 — — — — — — — Support 6 15 1.5 — — — — — — — Support 715 1.5 — — — — — — — Support 8 15 1.5 — — — — — — — Support 9 15 1.5 — —— — — — — Support 10 22 4 — — — — — — — Support 11 30 2.4 28 3 — — — — —Support 12 30 2.4 40 3 — — — — — Support 13 60 2.4 40 15 — — — — —Support 14 30 0.3 40 3 170 — 50 13 2.1 Support 15 30 2.4 40 3 — — — — —Support 16 4.5 1 — — 170 — 50 13 2.1 Support 17 4.5 1 40 4 170 — 50 132.1 Support 18 4.5 1 — — — 150 35 4.5 1.2 Support 19 4.5 1 40 8 — 150 354.5 2.1 Support 20 30 2.7 — — — — — — — Third anodization treatmentPhosphoric Sulfuric acid acid concentration concentration of of Averageelectrolytic electrolytic Current Coating pore solution solutionTemperature density amount diameter Support (g/l) (g/l) (° C.) (A/dm²)(g/m²) (nm) Support 1 — — — — — 30 Support 2 170 — 54 50 0.3 12 Support3 — — — — — 30 Support 4 — — — — — 30 Support 5 — — — — — 30 Support 6 —— — — — 30 Support 7 — — — — — 30 Support 8 — — — — — 30 Support 9 — — —— — 30 Support 10 — — — — — 7 Support 11 — — — — — 13 Support 12 — — — —— 30 Support 13 — — — — — 100 Support 14 — — — — — 30 Support 15 — — — —— 30 Support 16 — — — — — 40 Support 17 — — — — — 100 Support 18 — — — —— 40 Support 19 — — — — — 148 Support 20 — — — — — 7

Formation of Undercoat Layer (Examples 1 to 107)

The other surface of the support was coated with an undercoat layercoating solution (1) having the following composition such that thedrying coating amount was set to 20 mg/m², thereby forming an undercoatlayer.

[Undercoat Layer Coating Solution (1)]

-   -   Compound (UC-1) for undercoat layer (the following structure):        0.18 parts    -   Hydroxyethyl imino diacetic acid: 0.05 parts    -   Surfactant (EMALEX 710, manufactured by Nihon Emulsion Co.,        Ltd.): 0.03 parts    -   Water: 28.0 parts

Compound (UC-1) for Undercoat Layer

Formation of Undercoat Layer (Example 108 and Comparative Examples 7 to12)

In Example 108 and Comparative Examples 7 to 12, each undercoat layerwas formed in the same manner as in a case of using the followingundercoat layer coating solution (1) except that the following undercoatlayer coating solution (2) was used.

[Undercoat Layer Coating Solution (2)]

-   -   Compound (2) for undercoat layer having structure shown below:        0.18 parts    -   Tetrasodium ethylenediaminetetraacetate: 0.10 parts    -   Polyoxyethylene lauryl ether: 0.03 parts    -   Water: 61.39 parts

The numerical values on the lower right side of the parentheses of eachconstitutional unit in the compound (2) for an undercoat layer indicatethe mass ratios and the numerical values on the lower right side of theparentheses of each ethyleneoxy unit indicate repetition numbers.

<Formation of Image Recording Layer 1>

The undercoat layer of the support on which the undercoat layer wasformed was bar-coated with an image recording layer coating solution (2)having the following composition and dried in an oven at 70° for 60seconds, thereby forming an image recording layer having a dryingcoating amount of 0.6 g/m².

[Image Recording Layer Coating Solution (2)]

-   -   Thermoplastic polymer particle aqueous dispersion liquid (shown        below): 20.0 parts    -   Infrared absorbing agent (2) (the following structure): 0.2        parts    -   Polymerization initiator (IRGACURE 250, manufactured by BASF        SE): 0.4 parts    -   Polymerization initiator (2) (the following structure): 0.15        parts    -   Polymerizable compound SR-399 (manufactured by Sartomer Japan        Inc.): 1.50 parts    -   Mercapto-3-triazole: 0.2 parts    -   Byk336 (manufactured by BYK Chemie GmbH): 0.4 parts    -   Klucel M (manufactured by Hercules, Inc.): 4.8 parts    -   ELVACITE 4026 (manufactured by Ineos Acrylics Ltd.): 2.5 parts    -   Anionic surfactant 1 (the following structure): 0.15 parts    -   n-Propanol: 55.0 parts    -   2-Butanone: 17.0 parts

The compounds described with the trade names in the composition above asfollows.

-   -   IRGACURE 250:        (4-methylphenyl)[4-(2-methylpropyl)phenyl]iodonium=hexafluorophosphate        (75 mass % propylene carbonate solution)    -   SR-399: dipentaerythritolpentaacrylate    -   Byk336: modified dimethyl polysiloxane copolymer (25 mass %        xylene/methoxy propyl acetate solution)    -   Klucel M: hydroxypropyl cellulose (2 mass % aqueous solution)    -   ELVACITE 4026: highly branched polymethyl methacrylate (10 mass        % 2-butanone solution)

Further, Ph represents a phenyl group.

[Preparation of Thermoplastic Polymer Particle Aqueous DispersionLiquid]

Nitrogen gas was introduced into a four-necked flask equipped with astirrer, a thermometer, a dropping funnel, a nitrogen introduction pipe,and a reflux condenser, deoxygenation was performed, 10 parts ofpolyethylene glycol methyl ether methacrylate (PEGMA, average number ofrepeating units of ethylene glycol: 20), 200 parts of distilled water,and 200 parts of n-propanol were added thereto, and then the mixture washeated until the internal temperature thereof was set to 70° C. Next, amixture of 10 parts of styrene (St), 80 parts of acrylonitrile (AN), and0.8 parts of 2,2′-azobisisobutyronitrile prepared in advance was addeddropwise for 1 hour. After dropwise addition was finished, the reactionwas allowed to be continued for 5 hours, 0.4 parts of2,2′-azobisisobutyronitrile was added thereto, and the mixture washeated until the internal temperature was set to 80° C. Subsequently,0.5 g of 2,2′-azobisisobutyronitrile was added for 6 hours. The totaldegree of polymerization at the stage of the continued reaction for 20hours was 98% or greater, and a thermoplastic polymer particle aqueousdispersion liquid having PEGMA, St, and AN at a mass ratio of 10/10/80was obtained. The particle size distribution of the thermoplasticpolymer particle has a maximum value at 150 nm of the volume averageparticle diameter.

Here, the particle size distribution was acquired by imaging an electronmicrograph of polymer particles, measuring the total number of 5,000particle diameters of particles on the photograph, dividing the intervalfrom the maximum value of the obtained measured value of the particlediameter to 0 into the logarithmic scale of 50, and plotting theappearance frequency of each particle diameter. Further, the particlediameter of a spherical particle having the same particle area as theparticle area on the photograph was set to the particle diameter, asnon-spherical particles.

<Formation of Image Recording Layer 2>

The support or the undercoat layer, in a case where the support had anundercoat layer, was bar-coated with an image recording layer coatingsolution (1) with the following composition and dried in an oven at 100°for 60 seconds, thereby forming an image recording layer having a dryingcoating amount of 1.0 g/m².

The image recording layer coating solution (1) was obtained by mixing aphotosensitive solution (1) and a microgel solution (1) described belowimmediately before the coating and then stirring the solution.

[Image Recording Layer Coating Solution (1)]

—Photosensitive Solution (1)—

-   -   Binder polymer (1) (the following structure, Mw: 55,000 and n        (number of ethylene oxide (EO) repeating units): 2): 0.240 parts    -   Infrared absorbing agent (1) (the following structure): 0.020        parts    -   Borate compound (1) (Sodium tetraphenyl borate): 0.010 parts    -   Polymerization initiator (1) (the following structure): 0.162        parts    -   Polymerizable compound (tris(acryloyloxyethyl) isocyanurate, NK        ESTER A-9300, manufactured by Shin-Nakamura Chemical Co., Ltd.):        0.192 parts    -   Anionic surfactant 1 (the following structure): 0.050 g    -   Fluorine-based surfactant (1) (the following structure): 0.008        parts    -   2-Butanone: 1.091 parts    -   1-Methoxy-2-propanol: 8.609 g

(Microgel Solution (1))

-   -   Microgel (1): 2.640 parts    -   Distilled water: 2.425 parts

—Preparation of Microgel (1)—

A method of preparing a microgel (1) used for the microgel solution willbe described below.

<<Preparation of Polyvalent Isocyanate Compound (1)>>

0.043 parts of bismuth tris(2-ethylhexanoate) (NEOSTANN U-600(manufactured by NITTO KASEI CO., LTD.)) was added to an ethyl acetate(25.31 parts) suspension solution of 17.78 parts (80 parts by mmol) ofisophorone diisocyanate and 7.35 parts (20 parts by mmol) of thefollowing polyhydric phenol compound (1) and the solution was stirred.The reaction temperature was set to 50° at the time of heat generationbeing subsided, and the solution was stirred for 3 hours, therebyobtaining an ethyl acetate (50% by mass) solution of a polyvalentisocyanate compound (1).

<Preparation of Microgel (1)>

The following oil phase components and the water phase components weremixed with each other and emulsified at 12,000 rpm for 10 minutes usinga homogenizer. The obtained emulsion was stirred at 45° C. for 4 hours,5.20 parts of a 10 mass % aqueous solution of1,8-diazabicyclo[5.4.0]undeca-7-ene-octylate (U-CAT SA102, manufacturedby San-Apro Ltd.) was added thereto, and the solution was stirred atroom temperature for 30 minutes and allowed to stand at 45° C. for 24hours. The concentration of solid contents was adjusted to 20% by massusing distilled water, thereby obtaining an aqueous dispersion liquid ofthe microgel (1). The volume average particle diameter was measuredusing a dynamic light scattering type particle size distributionmeasuring device LB-500 (manufactured by Horiba Ltd.) according to alight scattering method, and the value was 0.28 μm.

(Oil Phase Components)

(Component 1) ethyl acetate: 12.0 parts

(Component 2) adduct (50 mass % ethyl acetate solution, manufactured byMitsui Chemicals, Inc.) obtained by adding trimethylolpropane (6 mol)and xylene diisocyanate (18 mol) and adding methyl one-terminalpolyoxyethylene (1 mol, repetition number of oxyethylene units: 90)thereto: 3.76 parts

(Component 3) polyvalent isocyanate compound (1) (as 50 mass % ethylacetate solution): 15.0 parts

(Component 4) 65 mass % solution of dipentaerythritol pentaacrylate(SR-399, manufactured by Sartomer Japan Inc.) in ethyl acetate: 11.54parts

(Component 5) 10% solution of sulfonate type surfactant (PIONINE A-41-C,manufactured by TAKEMOTO OIL & FAT Co., Ltd.) in ethyl acetate: 4.42parts

(Water Phase Components)

Distilled water: 46.87 g

<Formation of Image Recording Layer 3>

A water-based coating solution for an image recording layer containingcomponents such as the thermoplastic resin particles and the infraredabsorbing agent shown below was prepared, and the pH thereof wasadjusted to 3.6, the support was coated with the coating solution, anddried at 50° C. for 1 minute, thereby forming an image recording layer3.

A thermoplastic particle polymer SAN, an infrared absorbing agent IR-01,other components PAA, and the surfactant used in the coating solutionfor an image recording layer are as follows.

Thermoplastic resin particle SAN: styrene/acrylonitrile copolymer (molarratio of 50/50), average particle diameter: 61 nm, coating amount:0.6927 (g/m²)

Other components PAA: polyacrylic acid, weight-average molecular weight:250000, coating amount: 0.09 (g/m²)

Surfactant: Zonyl FSO100 (manufactured by Du Pont), coating amount:0.0075 (g/m²)

Infrared absorbing agent IR-01: infrared absorbing agent with thefollowing structure (Et represents an ethyl group), coating amount:1.03×10⁻⁴ (mol/m²)

<Formation of Image Recording Layer 4>

The undercoat layer was bar-coated with an image recording layer coatingsolution (3) with the following composition and dried in an oven at 100°for 60 seconds, thereby forming an image recording layer having a dryingcoating amount of 1.0 g/m².

The image recording layer coating solution (3) was obtained by mixing aphotosensitive solution (3) and a microgel solution (3) described belowimmediately before the coating and then stirring the solution.

[Photosensitive Solution (3)]

-   -   Binder polymer (1) [the following structure, Mw: 50000, n:        number of ethylene oxide (EO) units: 4]: 0.480 parts    -   Infrared absorbing agent (1) [the following structure]: 0.030        parts    -   Borate compound [Sodium tetraphenyl borate]: 0.014 parts    -   Polymerization initiator (1) [the following structure]: 0.234        parts    -   Radical polymerizable compound [tris(acryloyloxyethyl)        isocyanurate, NK ESTER A-9300, manufactured by Shin-Nakamura        Chemical Co., Ltd.]: 0.192 parts    -   Low-molecular weight hydrophilic compound (3)        [tris(2-hydroxyethyl)isocyanurate]: 0.052 parts    -   Anionic surfactant 1 [the following structure]: 0.099 g    -   Oil sensitizer phosphonium compound (3) [the following        structure]: 0.12 parts    -   Oil sensitizer ammonium group-containing polymer [the following        structure, reduced specific viscosity of 44 ml/g]: 0.035 parts    -   Oil sensitizer benzyl dimethyl octyl ammonium.PF₆ salt: 0.032        parts    -   Colorant ethyl violet [the following structure]: 0.030 part    -   Fluorine-based surfactant (1) [the following structure]: 0.02        parts    -   2-Butanone: 1.091 parts    -   1-Methoxy-2-propanol: 8.609 g

[Microgel Solution (3)]

-   -   Microgel (3): 1.580 parts    -   Distilled water: 1.455 parts

—Synthesis of Microgel (3)—

10 parts of an adduct (TAKENATE D-110N, manufactured by Mitsui Chemicalspolyurethanes, Inc.) of trimethylolpropane and xylene diisocyanate, 5.54parts of dipentaerythritol pentaacrylate (SR399, manufactured bySartomer Japan Inc.), and 0.1 parts of PIONINE A-41C (manufactured byTAKEMOTO OIL & FAT Co., Ltd.), as oil phase components, were dissolvedin 17 parts of ethyl acetate. As a water phase component, 40 parts of a4 mass % aqueous solution of PVA-205 was prepared. The oil phasecomponents and the water phase components were mixed with each other andemulsified at 12,000 rpm for 10 minutes using a homogenizer. 25 parts ofdistilled water was added to the obtained emulsion, and the resultantwas stirred at room temperature (25° C., the same applies hereinafter)for 30 minutes and stirred at 50° C. for 3 hours. The microgel solutionobtained in this manner was diluted with distilled water such that theconcentration of solid contents was set to 15% by mass, therebypreparing a microgel (3). The average particle diameter of the microgelmeasured by a light scattering method was 0.2 μm.

The subscripts of the parentheses indicating each constitutional unit ofthe ammonium group-containing polymer described above indicate thecontent (molar ratio) of each constitutional unit.

Formation of Protective Layer (Examples 1 to 107)

The image recording layer was bar-coated with a protective layer coatingsolution (1) with the following composition and dried in an oven at 120°C. for 60 seconds to form a protective layer having a drying coatingamount of 0.15 g/m².

[Protective Layer Coating Solution (1)]

-   -   Inorganic layered compound dispersion liquid (1) (shown below):        1.5 parts    -   Hydrophilic polymer (1) (the following structure, Mw: 30000)        (solid content): 0.03 parts    -   6 mass % aqueous solution of polyvinyl alcohol (CKS50, sulfonic        acid-modified, saponification degree of 99% by mole or greater,        degree of polymerization of 300, manufactured by Nippon        Synthetic Chemical Industry Co., Ltd.): 0.10 parts    -   6 mass % aqueous solution of polyvinyl alcohol (PVA-405,        saponification degree of 81.5% by mole, degree of polymerization        of 500, manufactured by KURARAY CO., LTD.): 0.03 parts    -   1 mass % aqueous solution of surfactant (EMALEX 710, the        following structure, manufactured by Nihon Emulsion Co., Ltd.):        0.86 parts    -   Ion exchange water: 6.0 parts

The subscripts of the parentheses indicating each constitutional unit ofthe hydrophilic polymer (1) indicate the content (molar ratio) of eachconstitutional unit. Further, the numerical values on the lower rightside of the parentheses of EMALEX 710 indicate repetition numbers.

[Preparation of Inorganic Layered Compound Dispersion Liquid (1)]

6.4 parts of synthetic mica SOMASIF ME-100 (manufactured by CO-OPCHEMICAL CO., LTD.) was added to 193.6 g of ion exchange water anddispersed such that the volume average particle diameter (laserscattering method) was set to 3 μm using a homogenizer. The aspect ratioof the obtained dispersed particles was 100 or greater.

Formation of Protective Layer (Example 108 and Comparative Examples 7 to12)

The image recording layer was bar-coated with a protective layer coatingsolution (3) with the following composition and dried in an oven at 120°C. for 60 seconds to form a protective layer having a drying coatingamount of 0.15 g/m², thereby preparing a lithographic printing plateprecursor.

[Protective Layer Coating Solution (3)]

-   -   Inorganic layered compound dispersion liquid (3) (obtained        below): 1.5 parts    -   Hydrophilic polymer (3) (solid content) [the following        structure, Mw: 30000]: 0.55 parts    -   6 mass % aqueous solution of polyvinyl alcohol (CKS50, sulfonic        acid-modified, saponification degree of 99% by mole or greater,        degree of polymerization of 300, manufactured by Nippon        Synthetic Chemical Industry Co., Ltd.): 0.10 parts    -   6 mass % aqueous solution of polyvinyl alcohol (PVA-405,        saponification degree of 81.5% by mole, degree of polymerization        of 500, manufactured by KURARAY CO., LTD.): 0.03 parts    -   80 mass % aqueous solution of surfactant (RAPISOL A-80 (trade        name), manufactured by NOF Corporation): 0.011 parts    -   Ion exchange water: 6.0 parts

The subscripts of the parentheses indicating each constitutional unit ofthe hydrophilic polymer (3) indicate the content (molar ratio) of eachconstitutional unit.

Example 1 to 18 and Comparative Examples 1 TO 6

<Formation of Resin Layer (Back Coat Layer)>

The surface of the support listed in Table 8 on a side opposite to aside where the image recording layer provided was bar-coated with acoating solution (1) for a back coat layer with the followingcomposition and dried in an oven at 120° C. for 60 seconds to form aresin layer (back coat layer) such that the film thickness after thedrying was set to 1 μm.

[Coating Solution (1) for Back Coat Layer]

-   -   PMMA (SUMIPEX (registered trademark) HT, manufactured by        Sumitomo Chemical Co., Ltd.): 5.0 parts by mass    -   Methyl ethyl ketone (MEK): 94.9 parts by mass    -   Fluorine-based surfactant (MEGAFACE F-780-F, manufactured by DIC        Corporation, 30 mass % solution of MEK): 0.1 parts by mass    -   Particles listed in Table 8: amount to obtain density listed in        Table 8

In Table 8, the notation of “no addition” in the columns of particlesindicates that the addition of particles was not performed.

<Formation of Undercoat Layer, Image Recording Layer, and ProtectiveLayer>

The undercoat layer, the image recording layer, and the protective layerlisted in Table 8 were formed on the support on which the back coatlayer was formed. The forming method is as described above.

In Table 8, the notation of “none” indicates that the correspondinglayer was not formed. The same applies to the tables shown below.

[Evaluation]

The following evaluations were performed on the obtained lithographicprinting plate precursors. The evaluation results are collectivelylisted in Table 8.

On-Press Development Delay Resistance (Examples 1 to 107)

The surface of the lithographic printing plate precursor where the imagerecording layer was provided was directly brought into contact with theopposite surface and this process was repeated until 50 sheets werelaminated, and the laminate was pressure-bonded by a pressure of 25kgf/cm² (2.45×10⁶ Pa) for 8 days. The lithographic printing plateprecursors on which the above-described operation was performed were setby Trendsetter 3244 (manufactured by Creo Co., Ltd.) and thenimage-exposed under conditions of resolution of 2400 dpi (dot per inch,1 inch is 2.54 cm), an output of 7 W, an external surface drum rotationspeed of 150 rpm, and a plate surface energy of 110 mJ/cm². Thelithographic printing plate precursors after image exposure were mountedon an offset rotary printing press (manufactured by TOKYO KIKAISEISAKUSHO, LTD.), and printing was performed on newsprint paper at aspeed of 100,000 sheets/hour using SOIBI KKST-S (red) (manufactured byInkTec Corporation) as printing ink for newspaper and ECO SEVEN N-1(manufactured by SAKATA INX CORPORATION) as dampening water. Theon-press development performed on the unexposed portion of the imagerecording layer on the printing press was completed, and the number ofsheets of printing paper required until the ink was not transferred tothe non-image area was counted as the number of on-press developmentsheets, and the scoring was made based on the following standard. Theevaluation results are listed in the columns of “on-press developmentdelay” in Table 8.

5: the number of on-press development sheets of lithographic printingplate precursors on which pressure bonding operation was notperformed+number of 3 or less of on-press development sheets

4: the number of on-press development sheets of lithographic printingplate precursors on which pressure bonding operation was notperformed+number of greater than 3 and 5 or less of on-press developmentsheets

3: the number of on-press development sheets of lithographic printingplate precursors on which pressure bonding operation was notperformed+number of greater than 5 and 10 or less on-press developmentsheets

2: the number of on-press development sheets of lithographic printingplate precursors on which pressure bonding operation was notperformed+number of greater than 10 and 15 or less of on-pressdevelopment sheets

1: the number of on-press development sheets of lithographic printingplate precursors on which pressure bonding operation was notperformed+number of greater than 15 and 30 or less of on-pressdevelopment sheets

Development Delay Resistance (Example 108 and Comparative Examples 7 to12)

In Example 108 and Comparative Examples 7 to 12, the development delayresistance in a case where the development was performed according tothe developer treatment system was evaluated.

The surface of the lithographic printing plate precursor where the imagerecording layer was provided was directly brought into contact with theopposite surface and this process was repeated until 50 sheets werelaminated, and the laminate was pressure-bonded by a pressure of 25kgf/cm² (2.45×10⁶ Pa) for 8 days. The lithographic printing plateprecursors on which the above-described operation was performed were setby Luxel PLATESETTER T-6000III (manufactured by Fujifilm Corporation)equipped with an infrared semiconductor laser and then exposed underconditions of a laser output of 70%, an external surface drum rotationspeed of 1000 rpm (for each time) and a resolution of 2400 dpi (dot perinch). A solid image and a 50% halftone dot chart were included in theexposed image.

Next, the development treatment was performed using the developer 1 withthe following composition and the automatic development treatment devicehaving a structure illustrated in FIG. 7, thereby obtaining alithographic printing plate.

The development treatment device exemplified in FIG. 7 is an automaticdevelopment treatment device including two rotary brush rolls 111. Abrush roll having an external diameter of 55 mm in which polybutyleneterephthalate fibers (diameter of bristles: 200 μm, length of bristle: 7mm) were implanted was used as the rotary brush roll 111, and the rollwas allowed to rotate 120 times (the peripheral speed of the brush tip:0.94 m/s) per minute in the same direction as the transportationdirection.

A lithographic printing plate precursor 130 after the exposure wascompleted was transported in the transportation direction illustrated inthe figure between two pairs of transport rolls 113 from a plate feedstand 118 to a plate discharge stand 119 at a transportation speed of 60cm/min on a transport guide plate 114 such that the lithographicprinting plate precursor 130 was allowed to pass through a space betweenthe rotary brush roll 111 and the transport guide plate 114.

In three spray pipes 115, the developer stored in a developer tank 120was supplied by a circulation pump 121 through a filter 117 using a pipeline 116, and the developer was supplied to the plate surface from eachspray pipe 115 by performing showering. Further, the volume of thedeveloper tank 120 was 20 liters, and the developer was recycled. Thelithographic printing plate discharged from the development treatmentdevice was dried by a dryer 122 without being washed with water. Afterthe development was completed, the scoring was made based on thefollowing standard. The evaluation results are listed in the columns of“development delay” in Table 9.

[Evaluation Method]

Each lithographic printing plate having a size of 5 cm×5 cm afterdevelopment was observed using a 25 magnification loupe, and the numberof residual films was counted.

[Evaluation Standard]

5: The number of residual films was 0.

4: The number of residual films was 1 or 2.

3: The number of residual films was in a range of 3 to 10.

2: The number of residual films was in a range of 11 to 50.

1: The number of residual films was 50 or greater.

[Developer 1]

-   -   Surfactant-1 shown below (PELEX NBL, manufactured by Kao        Corporation): 7.43 parts    -   Surfactant-2 shown below (NEWCOL B13, manufactured by Nippon        Nyukazai Co., Ltd.): 1.45 parts    -   Surfactant-3 shown below (SURFYNOL 2502, manufactured by Air        Products and Chemicals, Inc.): 0.4 parts    -   Benzyl alcohol: 0.6 parts    -   Sodium gluconate: 2.77 parts    -   Disodium monohydrogenphosphate: 0.3 parts    -   Sodium hydrogen carbonate: 0.22 parts    -   Antifoaming agent (SILCOLAPSE 432, manufactured by Bluestar        Silicones): 0.005 parts    -   Water: 86.83 parts

<Setter Plate Feeding Property (Plate Feeding Property)>

A laminate obtained by stacking 100 sheets of lithographic printingplate precursors directed to the same direction without usinginterleaving paper was set in a CTP plate setter “AMZI setter”(manufactured by NEC Engineering, Ltd.), and an operation of taking outone plate at a time from the uppermost portion of the laminate wascontinuously performed 100 times. The imparting of the plate-separatingproperty at this time was evaluated based on the following standard. Theevaluation was made by performing sensory evaluation with a score of 1to 5, and the evaluation results are listed in the columns of the “platefeeding property” in Table 8. A value of 2 or greater is in a practicallevel and a value of 3 or greater is preferable.

5: The occurrence frequency of a phenomenon in which the next plate wasnot raised at the time of lifting up a plate was 100%.

4: A phenomenon in which the next plate was raised at the time oflifting up a plate and did not fall quickly, but was peeled off withoutthe operation of separating the plate occurred. However, the occurrencefrequency was 1% or less with respect to the whole operations.

3: A phenomenon in which the next plate was raised at the time oflifting up a plate and was not peeled off by the first operation ofseparating the plate occurred. However, the occurrence frequency was 1%or less with respect to the whole operations.

2: The occurrence frequency of a phenomenon in which the next plate wasraised at the time of lifting up a plate and was not peeled off by thefirst operation of separating the plate was greater than 1% and 5% orless with respect to the whole operations.

1: The occurrence frequency of a phenomenon in which the next plate wasraised at the time of lifting up a plate and was not peeled off by thefirst operation of separating the plate was greater than 5% with respectto the whole operations.

<Measurement of Arithmetic Average Height Sa>

The arithmetic average height Sa was measured in conformity with themethod described in ISO 25178. In other words, three or more sites wereselected from the same sample and measured using a micromap MM3200-M100(manufactured by Mitsubishi Chemical Systems, Inc.), and the averagevalue of the obtained values was set as the arithmetic average heightSa. A measurement range with a size of 1 cm×1 cm was randomly selectedfrom the surface of the sample and the measurement was performed.

<Measurement of Bekk Smoothness (Bekk Second)>

The Bekk smoothness was measured in conformity with JIS P8119 (1998).The measurement was performed at one tenth the amount of standard air,in other words, an air amount of 1 mL using a Bekk smoothness tester(manufactured by KUMAGAI RIKI KOGYO Co., Ltd.). In a case where the Bekksmoothness was short, this indicates that the air release property ofthe contact surfaces of the lithographic printing plate precursorsvertically adjacent to each other was excellent at the time of forming alaminate by laminating the lithographic printing plate precursors andthe lithographic printing plate precursors were unlikely to be bonded toone another.

TABLE 8 Side opposite to side where image Side where recording layer isprovided image recording Evaluation results Bekk layer is providedOn-press Particle smooth- Under- Image Pro- develop- Plate diameterDensity Sa ness coat recording tective ment feeding Particle [μm][pcs/m²] [μm] [s] Support layer layer layer delay property Example 1MP-2200 0.3 500 0.3 1000 2 Present 2 Present 5 2 2 GR-300 25 8000 20 4 2Present 2 Present 2 5 transparent 3 MP-1451 0.1 5000 0.4 750 2 Present 2Present 5 3 4 MP-2200 0.3 5000 0.6 500 2 Present 2 Present 5 4 5 MX-40T0.5 5000 0.8 300 2 Present 2 Present 5 5 6 MX-300 3.2 5000 3.3 60 2Present 2 Present 5 5 7 MX-500H 5.3 5000 5.4 40 2 Present 2 Present 5 58 MR-7GC 6.5 5000 6.6 30 2 Present 2 Present 5 5 9 MBX-8 7.4 5000 7 25 2Present 2 Present 5 5 10 MX-1000 10 5000 10 15 2 Present 2 Present 4 511 MX-2000 20 5000 20 5 2 Present 2 Present 3 5 12 MX-300 3.2 400 0.32900 2 Present 2 Present 5 2 13 MX-300 3.2 500 0.4 750 2 Present 2Present 5 3 14 MX-300 3.2 1000 0.75 350 2 Present 2 Present 5 4 15MX-300 3.2 50000 10.5 15 2 Present 2 Present 5 5 16 MX-300 3.2 100000 128 2 Present 2 Present 4 5 17 MX-300 3.2 500000 18 5 2 Present 2 Present3 5 18 MX-300 3.2 600000 20 4 2 Present 2 Present 2 5 Comparative 1MX-40T 0.5 100 0.23 1080 2 Present 2 Present 5 1 Example 2 Micromer0.025 40000 0.21 1180 2 Present 2 Present 5 1 01-00-251 3 MBX-8 7.4600000 25 2 2 Present 2 Present 1 5 4 MX-3000 30 10000 40 1 2 Present 2Present 1 5 5 No addition 0.2 1200 1 Absent 1 Absent 5 1 6 No addition0.2 1200 2 Present 2 Present 5 1

The details of the abbreviations in Table 8 are as follows.

MP-2200: non-crosslinked acrylic particles, average particle diameter of0.3 μm, manufactured by Soken Chemical & Engineering Co., Ltd.

GR-300 transparent: crosslinked acrylic beads, average particle diameterof 25 μm, manufactured by Negami Chemical Industrial Co., Ltd.

MP-1451: non-crosslinked acrylic particles, average particle diameter of0.1 μm, manufactured by Soken Chemical & Engineering Co., Ltd.

MX-40T: crosslinked acrylic monodisperse particles, average particlediameter of 0.5 μm, manufactured by Soken Chemical & Engineering Co.,Ltd.

MX-300: crosslinked acrylic monodisperse particles, average particlediameter of 3.2 μm, manufactured by Soken Chemical & Engineering Co.,Ltd.

MX-500H: crosslinked acrylic monodisperse particles, average particlediameter of 5.3 μm, manufactured by Soken Chemical & Engineering Co.,Ltd.

MR-7GC: crosslinked acrylic polydisperse particles, average particlediameter of 6.5 μm, manufactured by Soken Chemical & Engineering Co.,Ltd.

MBX-8: crosslinked methyl polymethacrylate, average particle diameter of7.4 μm, manufactured by Sekisui Plastics Co., Ltd.

MX-1000: crosslinked acrylic monodisperse particles, average particlediameter of 10 μm, manufactured by Soken Chemical & Engineering Co.,Ltd.

MX-2000: crosslinked acrylic monodisperse particles, average particlediameter of 20 μm, manufactured by Soken Chemical & Engineering Co.,Ltd.

Micromer 01-00-251: micromer (registered trademark) 01-00-251,polystyrene, average particle diameter of 25 nm, manufactured byCorefront Corporation

MX-3000: crosslinked acrylic monodisperse particles, average particlediameter of 30 μm, manufactured by Soken Chemical & Engineering Co.,Ltd.

Based on the results of Examples 1 to 18 and Comparative Examples 1 to6, it was understood that each of the lithographic printing plateprecursors according to the present disclosure, in which the arithmeticaverage height Sa of the surface of the outermost layer on a sideopposite to a side where the image recording layer is provided is in arange of 0.3 μm to 20 μm, has an excellent on-press development delayresistance and an excellent plate feeding property of taking out aprecursor from a laminate.

Examples 19 to 36 and 99 to 108 and Comparative Example 7 to 12

The formation of resin layers (back coat layers) and the formation andevaluation of the undercoat layers, image recording layers, andprotective layers were performed in the same manner as in Examples 1 to18.

The details of the formed layers and evaluation results are listed inTable 9.

TABLE 9 Side opposite to side where image recording layer is providedSide where image recording Evaluation results Bekk layer is providedOn-press Particle smooth- Under- Image Pro- develop- Plate diameterDensity Sa ness coat recording tective ment feeding Particle [μm][pcs/m²] [μm] [s] Support layer layer layer delay property Example 19MP-2200 0.3 500 0.3 1000 1 Absent 1 Absent 5 2 20 GR-300 25 8000 20 4 1Absent 1 Absent 2 5 transparent 21 MP-1451 0.1 5000 0.4 750 1 Absent 1Absent 5 3 22 MP-2200 0.3 5000 0.6 500 1 Absent 1 Absent 5 4 23 MX-40T0.5 5000 0.8 300 1 Absent 1 Absent 5 5 24 MX-300 3.2 5000 3.3 60 1Absent 1 Absent 5 5 25 MX-500H 5.3 5000 5.4 40 1 Absent 1 Absent 5 5 26MR-7GC 6.5 5000 6.6 30 1 Absent 1 Absent 5 5 27 MBX-8 7.4 5000 7 25 1Absent 1 Absent 5 5 28 MX-1000 10 5000 10 15 1 Absent 1 Absent 4 5 29MX-2000 20 5000 20 5 1 Absent 1 Absent 3 5 30 MX-300 3.2 400 0.32 900 1Absent 1 Absent 5 2 31 MX-300 3.2 500 0.4 750 1 Absent 1 Absent 5 3 32MX-300 3.2 1000 0.75 350 1 Absent 1 Absent 5 4 33 MX-300 3.2 50000 10.515 1 Absent 1 Absent 5 5 34 MX-300 3.2 100000 12 8 1 Absent 1 Absent 4 535 MX-300 3.2 500000 18 5 1 Absent 1 Absent 3 5 36 MX-300 3.2 600000 204 1 Absent 1 Absent 2 5 99 MX-300 3.2 5000 3.3 60 11 Absent 1 Absent 5 5100 MX-300 3.2 5000 3.3 60 12 Absent 1 Absent 5 5 101 MX-300 3.2 50003.3 60 13 Absent 1 Absent 5 5 102 MX-300 3.2 5000 3.3 60 14 Absent 1Absent 5 5 103 MX-300 3.2 5000 3.3 60 15 Absent 1 Absent 5 5 104 MX-3003.2 5000 3.3 60 16 Absent 1 Absent 5 5 105 MX-300 3.2 5000 3.3 60 17Absent 1 Absent 5 5 106 MX-300 3.2 5000 3.3 60 18 Absent 1 Absent 5 5107 MX-300 3.2 5000 3.3 60 19 Absent 1 Absent 5 5 Side opposite to sidewhere image Side where image Evaluation results recording layer isprovided recording layer is provided On-press Particle Bekk Under- ImagePro- develop- Plate diameter Density Sa smoothness coat recordingtective ment feeding Particle [μm] [pcs/m²] [μm] [s] Support layer layerlayer delay property Example 108 MX-300 3.2 5000 3.3 60 20 Present 4Present 5 5 Comparative Example 7 MX-40T 0.5 100 0.23 1080 20 Present 4Present 5 1 Comparative Example 8 Micromer 0.025 40000 0.21 1180 20Present 4 Present 5 1 01-00-251 Comparative Example 9 MBX-8 7.4 60000025 2 20 Present 4 Present 2 5 Comparative Example 10 MX-3000 30 10000 401 20 Present 4 Present 1 5 Comparative Example 11 No addition 0.2 120020 Present 4 Present 5 1 Comparative Example 12 No addition 0.2 1200 20Present 4 Present 5 1

Based on the results of Examples 19 to 36 and Examples 99 to 107, it wasunderstood that each of the lithographic printing plate precursorsaccording to the present disclosure, in which the arithmetic averageheight Sa of the surface of the outermost layer on a side opposite to aside where the image recording layer is provided is in a range of 0.3 μmto 20 μm, has an excellent on-press development delay resistance and anexcellent plate feeding property of taking out a precursor from alaminate.

Based on the results of Example 108 and Comparative Examples 7 to 12, itwas understood that each of the lithographic printing plate precursorsaccording to the present disclosure, in which the arithmetic averageheight Sa of the surface of the outermost layer on a side opposite to aside where the image recording layer is provided is in a range of 0.3 μmto 20 μm, has an excellent development delay resistance and an excellentplate feeding property of taking out a precursor from a laminate even ina case where the development is performed according to the developertreatment system.

Examples 37 to 54

The formation of resin layers (back coat layers) and the formation andevaluation of the undercoat layers, image recording layers, andprotective layers were performed in the same manner as in Examples 1 to18.

The details of the formed layers and evaluation results are listed inTable 10.

TABLE 10 Side where image recording Side opposite to side where layer isprovided image recording layer is provided Evaluation results BekkOn-press Particle smooth- Under- Image Pro- develop- Plate diameterDensity Sa ness coat recording tective ment feeding Particle [μm][pcs/m²] [μm] [s] Support layer layer layer delay property Example 37MP-2200 0.3 500 0.3 1000 10 Absent 3 Absent 4 2 38 GR-300 25 8000 20 410 Absent 3 Absent 2 5 transparent 39 MP-1451 0.1 5000 0.4 750 10 Absent3 Absent 4 3 40 MP-2200 0.3 5000 0.6 500 10 Absent 3 Absent 4 4 41MX-40T 0.5 5000 0.8 300 10 Absent 3 Absent 4 4 42 MX-300 3.2 5000 3.3 6010 Absent 3 Absent 4 4 43 MX-500H 5.3 5000 5.4 40 10 Absent 3 Absent 5 544 MR-7GC 6.5 5000 6.6 30 10 Absent 3 Absent 4 5 45 MBX-8 7.4 5000 7 2510 Absent 3 Absent 4 5 46 MX-1000 10 5000 10 15 10 Absent 3 Absent 3 547 MX-2000 20 5000 20 5 10 Absent 3 Absent 3 5 48 MX-300 3.2 400 0.32900 10 Absent 3 Absent 4 2 49 MX-300 3.2 500 0.4 750 10 Absent 3 Absent4 3 50 MX-300 3.2 1000 0.75 350 10 Absent 3 Absent 4 3 51 MX-300 3.250000 10.5 15 10 Absent 3 Absent 4 4 52 MX-300 3.2 100000 12 8 10 Absent3 Absent 3 5 53 MX-300 3.2 500000 18 5 10 Absent 3 Absent 3 5 54 MX-3003.2 600000 20 4 10 Absent 3 Absent 2 5

Based on the results of Examples 37 to 54, it was understood that eachof the lithographic printing plate precursors according to the presentdisclosure, in which the arithmetic average height Sa of the surface ofthe outermost layer on a side opposite to a side where the imagerecording layer is provided is in a range of 0.3 μm to 20 μm, has anexcellent on-press development delay resistance and an excellent platefeeding property of taking out a precursor from a laminate.

Examples 55 to 68

The formation of resin layers (back coat layers) and the formation andevaluation of the undercoat layers, image recording layers, andprotective layers were performed in the same manner as in Examples 1 to18. The details of the formed layers and evaluation results are listedin Table 11.

Further, the film thickness of each resin layer was measured, theparticle embedment rate was calculated according to the followingequation, and the results are listed in Table 11.

Particle embedment rate=(the film thickness of the resin layer/theaverage particle diameter of the particles contained in the resin layer)

The film thickness of the resin layer was obtained by cutting thelithographic printing plate precursor using a microtome and measuringthe cross section using a scanning electron microscope.

Further, the falling of particles was evaluated according to thefollowing evaluation method.

<Evaluation of Falling of Particles>

After the humidity of the lithographic printing plate precursors wasadjusted in an environment of 25° at a relative humidity (RH) of 60% for2 hours, each precursor was punched into a size of 2.5 cm×2.5 cm andattached to a continuous load type scratch resistance strength testerTYPE-18 (manufactured by SHINTO Scientific Co., Ltd.), the rear surfaceof the punched lithographic printing plate precursor was set to bebrought into contact with the surface of the lithographic printing plateprecursor which had not been punched, and several sites of thelithographic printing plate precursor were scratched by applying a loadof 0 to 1500 gf (0 to 14.7 N). The scratched rear surface was observedvisually and using a scanning electron microscope (SEM), and the fallingof the particles from the back coat layer was evaluated based on thefollowing standard. The evaluation was made by performing sensoryevaluation with a score of 1 to 5, and a value of 3 or greater is in apractically preferable level. The evaluation results are listed in Table11.

5: The falling of particles was not found when observed visually orobserved using an SEM.

4: The falling of particles was not found when observed visually, butwas able to be slightly found when observed using an SEM.

3: The falling of particles was not found when observed visually, butwas able to be found when observed using an SEM.

2: The falling of particles was partially found when observed visually,but was able to be slightly found when observed using an SEM.

1: The falling of particles was able to be clearly found when simplyobserved visually.

TABLE 11 Side opposite to side where image recording layer is providedSide where Thick- image recording Evaluation results ness Particle layeris provided On-press Particle of resin embed- Under- Image Pro- develop-Plate Falling diameter Density Sa layer ment coat recording tective mentfeeding of Particle [μm] [pcs/m²] [μm] [μm] rate Support layer layerlayer delay property particle Example 55 MX-300 3.2 5000 3.4 0.5 0.16 1Absent 1 Absent 5 5 3 56 MX-300 3.2 5000 3.4 0.6 0.19 1 Absent 1 Absent5 5 4 57 MX-300 3.2 5000 3.3 1 0.31 1 Absent 1 Absent 5 5 5 58 MX-3003.2 5000 2.6 1.5 0.47 1 Absent 1 Absent 4 5 5 59 MX-300 3.2 5000 2.5 1.60.50 1 Absent 1 Absent 4 5 5 60 MX-300 3.2 5000 2.2 2 0.63 1 Absent 1Absent 4 5 5 61 MX-300 3.2 5000 1.5 2.5 0.78 1 Absent 1 Absent 3 5 5 62MBX-8 7.4 5000 7.1 0.5 0.07 1 Absent 1 Absent 5 5 2 63 MBX-8 7.4 50007.1 0.6 0.08 1 Absent 1 Absent 5 5 3 64 MBX-8 7.4 5000 7.0 1 0.14 1Absent 1 Absent 5 5 3 65 MBX-8 7.4 5000 7.0 1.5 0.20 1 Absent 1 Absent 55 5 66 MBX-8 7.4 5000 6.5 1.6 0.22 1 Absent 1 Absent 4 5 5 67 MBX-8 7.45000 5.5 2 0.27 1 Absent 1 Absent 4 5 5 68 MBX-8 7.4 5000 4.5 2.5 0.34 1Absent 1 Absent 2 5 5

Based on the results of Examples 55 to 68, it was understood that eachof the lithographic printing plate precursors according to the presentdisclosure has an excellent development delay resistance and anexcellent plate feeding property of taking out a precursor from alaminate and the falling of particles is suppressed in a case whereparticularly the particle embedment rate is in a range of 0.2 to 0.5.

Examples 69 to 77

The formation of resin layers (back coat layers) and the formation andevaluation of the undercoat layers, image recording layers, andprotective layers were performed in the same manner as in Examples 1 to18 except that the PMMA used for forming a resin layer (back coat layer)and contained, as a binder, in the coating solution (1) for a back coatlayer was changed to the binder listed in Table 12. The details of theformed layers and evaluation results are listed in Table 12.

Further, the respective SP values of the binder and particles containedin the resin layer were calculated according to the method describedabove, and the absolute value of the difference (difference in SP value)is listed in Table 12.

Moreover, the hardness (10% hardness) of particles was measuredaccording to the method described above, and the measurement results(hardness) are listed in Table 12.

In addition, the evaluation of particle dispersibility was performedaccording to the following evaluation method.

<Particle Dispersibility>

A total area of 4 mm² of the surface of each resin layer (back coatlayer) formed according to the method described above was randomlyobserved using an SEM (×400 times) and imaged, and determination wasmade based on whether the particles were in contact or not.

5 points: The particles were not in contact with each other.

4 points: The maximum of two particles were in contact with each other.

3 points: The maximum of 3 to 5 particles were in contact with eachother, but the frequency was 30% or less.

2 points: There was an aggregate formed of the maximum of 5 or lessparticles, and the frequency was greater than 30%.

1 point: There was an aggregate formed of the maximum of 6 or moreparticles

TABLE 12 Side opposite to side where Side where image recording layer isprovided image recording Evaluation results Dif- layer is provided On-Particle ference Image press di- in SP Hard- Under- re- Pro- develop-Plate Particle ameter Density Sa value ness coat cording tective mentfeeding dispers- Binder Particle [μm] [pcs/m²] [μm] [MPa^(1/2)] [MPa]Support layer layer layer delay property ibility Ex- 69 PMMA Acryl 5.05000 5.1 0.4 23 1 Absent 1 Absent 5 5 5 ample 70 PMMA Urethane 6.0 50005.6 1.3 8 1 Absent 1 Absent 5 5 4 71 PMMA Styrene 5.0 5000 4.8 0.8 15 1Absent 1 Absent 5 5 4 72 PMMA Poly- 6.0 5000 5.5 2.3 1.5 1 Absent 1Absent 5 5 4 ethylene 73 Urethane Urethane 5.0 5000 4.5 0.3 1 1 Absent 1Absent 5 5 5 74 Styrene Styrene 5.0 5000 4.7 0.3 15 1 Absent 1 Absent 55 5 75 PVA Acryl 5.0 5000 4.8 4 23 1 Absent 1 Absent 5 5 3 76 PMMASilica 5.0 5000 4.9 13 80 1 Absent 1 Absent 4 5 2 77 PMMA WC 5.0 5000 5— 100 or 1 Absent 1 Absent 3 5 2 greater

Based on the results of Examples 69 to 77, it was understood that eachof the lithographic printing plate precursors according to the presentdisclosure has an excellent development delay resistance and anexcellent plate feeding property of taking out a precursor from alaminate and the dispersibility of particles is improved in a case wherethe difference in solubility parameter between the particles and thebinder is 4 MPa^(1/2) or less.

Further, it was found that particularly the on-press development delayresistance is excellent in a case where the hardness of particles is 80MPa or less.

The abbreviations in Table 12 other than those described above are asfollows.

[Binder]

-   -   Urethane: OLESTER (registered trademark) RA1500, polyurethane        resin, manufactured by Mitsui Chemicals, Inc.    -   Styrene: ESPOLEX SB, styrene-based elastomer, manufactured by        Sumitomo Chemical Co., Ltd.    -   PVA: 5% aqueous solution of PVA 405, polyvinyl alcohol resin,        manufactured by Kuraray Co., Ltd.

[Particles]

-   -   Acryl: MX-500H, crosslinked acrylic monodisperse particles,        manufactured by Soken Chemical & Engineering Co., Ltd.    -   Urethane: AK-800TR, urethane beads, manufactured by Negami        Chemical Industrial Co., Ltd.    -   Styrene: SX-500H, crosslinked styrene monodisperse particles,        manufactured by Soken Chemical & Engineering Co., Ltd.    -   Polyethylene: CHEMIPEARL V300, polyolefin aqueous dispersion,        manufactured by Mitsui Chemicals, Inc.    -   Silica: sicastar (registered trademark) 43-00-503, silica        particles, manufactured by Corefront Corporation    -   WC: tungsten carbide, WC-50, manufactured by Japan New Metals        Co., Ltd.

Examples 78 to 85

<Uneven Shape>

After a coating solution (1) for forming protrusions with the followingcomposition was prepared, protrusions were formed, according to thefollowing means 1 or means 2, on the surface of the outermost layer on aside opposite to a side where the image recording layer was provided.

The method to be used between the means 1 and the means 2 is listed inTable 13.

[Coating Solution (1) for Forming Protrusions]

-   -   PMMA (SUMIPEX (registered trademark) HT, manufactured by        Sumitomo Chemical Co., Ltd.): 5.0 parts by mass    -   Methyl ethyl ketone (MEK): 94.9 parts by mass    -   Fluorine-based surfactant (MEGAFACE F-780-F, manufactured by DIC        Corporation, 30 mass % solution of MEK): 0.1 parts by mass

Based on the formulation described above, a predetermined sample wasprepared by adjusting the PMMA concentration and the accompanying airpressure of a two-fluid spray.

[Means 1]

The surface of the outermost layer on a side opposite to a side wherethe image recording layer was provided was coated with the coatingsolution (1) for forming protrusions using a spray and an Atomax AM6type nozzle (manufactured by Atmax, Inc.), and the solution was dried at120° C. for 90 seconds.

The spray coating amount was set such that the average height and thedensity of protrusions were set to the values listed in Table 13.

[Means 2]

The surface of the outermost layer on a side opposite to a side wherethe image recording layer was provided was coated with the coatingsolution (1) for forming protrusions such that the dried film thicknesswas set to 1 μm using a wire bar (No. 10 bar (18.25 mL/m²)), and thesolution was dried at 120° C. for 90 seconds. The dried film obtained bybeing dried was coated with the coating solution (1) for formingprotrusions using a spray and an Atomax AM6 type nozzle (manufactured byAtmax, Inc.), and the solution was dried at 120° C. for 90 seconds.

<Formation of Undercoat Layers, Image Recording Layers, and ProtectiveLayers>

The formation of resin layers (back coat layers) and the formation andevaluation of the undercoat layers, image recording layers, andprotective layers were performed in the same manner as in Examples 1 to18.

The details of the formed layers and evaluation results are listed inTable 13.

TABLE 13 Side opposite to side where image recording layer is providedSide where image recording Evaluation results Average Bekk layer isprovided On-press Means for height of smooth- Under- Image develop-Plate forming protrusions Density Sa ness coat recording Protective mentfeeding unevenness [μm] [pcs/m²] [μm] [s] Support layer layer layerdelay property Example 78 1 1 4000 0.4 600 1 Absent 1 Absent 5 2 79 1 1100000 0.7 400 1 Absent 1 Absent 5 3 80 1 5 3000 2.9 75 1 Absent 1Absent 5 4 81 1 10 5000 6 35 1 Absent 1 Absent 4 5 82 1 10 500 0.5 500 1Absent 1 Absent 4 3 83 1 20 4000 15 7 1 Absent 1 Absent 3 5 84 1 25 500022 4 1 Absent 1 Absent 2 5 85 2 5 3000 2.9 75 1 Absent 1 Absent 5 4

Based on the results of Examples 78 to 85, it was understood that eachof the lithographic printing plate precursors according to the presentdisclosure has an excellent on-press development delay resistance and anexcellent plate feeding property of taking out a precursor from alaminate even in a case of an aspect in which the rear surface hasprotrusions.

Further, it was understood that particularly the on-press developmentdelay resistance is excellent in a case where the average height ofprotrusions is in a range of 0.5 μm to 20 μm.

Examples 86 to 91

<Resin Layer (Formation of Back Coat Layer)>

The resin layers were formed according to the same method as in Examples1 to 18.

<Formation of Image Recording Layer>

The image recording layers were formed according to the same method asin Examples 1 to 18 except that particles were further added to theimage recording layer coating solution (2) in the formation of the imagerecording layer 1. The details of the added particles are listed inTable 14.

Thereafter, the Bekk smoothness of the rear surface and the Bekksmoothness of the front surface were measured, and the measurementresults are listed in Table 14. Further, the on-press development delayand the plate feeding property were evaluated according to the samemethod as in Examples 1 to 18, and the evaluation results are listed inTable 14. The description of “1/a+1/b” in Table 14 indicates the valueobtained by “1/a+1/b” in a case where the Bekk smoothness of the frontsurface is set as a seconds and the Bekk smoothness of the rear surfaceis set as b seconds.

TABLE 14 Side opposite to side where image recording layer is providedBekk Particle smoothness diameter Density Sa (b) Particle [μm] [pcs/m²][μm] [s] Support Example 86 MP-2200 0.3 500 0.3 1000 1 87 MP-2200 0.3500 0.3 1000 1 88 MP-2200 0.3 500 0.3 1000 1 89 MP-2200 0.3 500 0.3 10001 90 MP-2200 0.3 500 0.3 1000 1 91 MP-2200 0.3 500 0.3 1000 1 Side whereimage recording layer is provided Evaluation results Bekk smooth-On-press Image Particle ness 1/a + develop- Plate Undercoat recordingProtective diameter Density Sa (a) 1/b ment feeding layer layer layerParticle [μm] [pcs/m²] [μm] [s] [1/s] delay property Example 86 Absent 1Absent Absent Absent Absent 0.2 1200 0.0018 5 2 87 Absent 1 AbsentMX-40T 0.5 1000 0.3 1000 0.0020 2 5 88 Absent 1 Absent MX-30H3wT 0.81000 0.5 600 0.0027 5 3 89 Absent 1 Absent MX-30H3wT 0.8 5000 0.8 3000.0043 5 4 90 Absent 1 Absent ART PEARL J-SP 3.2 1000 1.9 110 0.0101 5 591 Absent 1 Absent ART PEARL J-6P 6.3 1000 2.9 68 0.0157 5 5

Based on the results of Examples 86 to 91, it was understood that eachof the lithographic printing plate precursors according to the presentdisclosure has an excellent development delay resistance and anexcellent plate feeding property of taking out a precursor from alaminate in a case where both expressions of a 1000 and 1/a+1/b 0.002are satisfied.

Examples 92 to 98

The formation of resin layers (back coat layers) and the formation andevaluation of the undercoat layers, image recording layers, andprotective layers were performed in the same manner as in Example 25except that the support listed in Table 15 was used as a support.Further, the scratch resistance was evaluated as follows.

In Examples 92 to 98, the arithmetic average height Sa and the Bekksmoothness of the surface of the outermost layer on a side opposite to aside where the image recording layer is provided are the same as thearithmetic average height Sa and the Bekk smoothness in Example 25.

<Evaluation of Scratch Resistance>

After the humidity of the lithographic printing plate precursors wasadjusted in an environment of 25° at a relative humidity (RH) of 60% for2 hours, a precursor was punched into a size of 2.5 cm×2.5 cm andattached to a continuous load type scratch resistance strength testerTYPE-18 (manufactured by SHINTO Scientific Co., Ltd.), the rear surfaceof the lithographic printing plate precursor which had been punched wasset to be brought into contact with the surface of the lithographicprinting plate precursor which has not been punched, and several sitesof the lithographic printing plate precursor were scratched by applyingthe pressure listed in Table 15. The scratched lithographic printingplate precursor was set by Trendsetter 3244 (manufactured by Creo Co.,Ltd.) and then image-exposed under conditions of resolution of 2400 dpi,an output of 7 W, an external surface drum rotation speed of 150 rpm,and a plate surface energy of 110 mJ/cm². The lithographic printingplate precursor after image exposure was mounted on an offset rotaryprinting press (manufactured by TOKYO KIKAI SEISAKUSHO, LTD.), andprinting was performed on newsprint paper at a speed of 100,000sheets/hour using SOMI KKST-S (red) (manufactured by InkTec Corporation)as printing ink for newspaper and ECO SEVEN N-1 (manufactured by SAKATAINX CORPORATION) as dampening water. In the above-described printingprocess, 1,000-th printed matter was sampled, the degree of scratchesand stain caused by scratches was visually observed.

The evaluation was made by performing sensory evaluation with a score of1 to 5, and a value of 3 or greater is in a practically preferablelevel.

5: Scratches and stain were not found.

4: Although scratches and stain were not confirmed by visualrecognition, scratches and stain which were able to be confirmed using a6 magnification loupe were found at one site.

3: Although scratches and stain were not confirmed by visualrecognition, scratches and stain which were able to be confirmed using a6 magnification loupe were found at several sites.

2: Scratches and stain which were able to be confirmed by visualrecognition were found at several sites.

TABLE 15 Evaluation results On-press Plate Pressure development feedingScratch Support [kgf/m²] delay property resistance Example 92 5 15 5 5 393 3 15 5 5 4 94 4 15 5 5 4 95 6 15 5 5 5 96 7 15 4 5 5 97 8 15 3 5 5 989 15 2 5 5

Further, the unit of the pressure listed in Table 15 is kgf/m² and 1kgf/m² is 9.80665 Pa.

Based on the results of Examples 92 to 97, it was understood that eachof the lithographic printing plate precursors according to the presentdisclosure has an excellent on-press development delay resistance and anexcellent plate feeding property of taking out a precursor from alaminate in a case where a support after 1 hour to 1 year from theanodization treatment is used.

It was understood that each of the lithographic printing plateprecursors according to the present disclosure has an excellent scratchresistance in a case where a support after 1 day to 1 year from theanodization treatment is used.

The disclosure of JP2017-072052 filed on Mar. 31, 2017 is incorporatedin the present specification by reference.

All documents, patent applications, and technical standards described inthe present specification are incorporated herein by reference to thesame extent as in a case of being specifically and individually notedthat individual documents, patent applications, and technical standardsare incorporated by reference.

EXPLANATION OF REFERENCES

-   -   1, 18: aluminum plate    -   2, 4: roller-like brushes    -   3: polishing slurry liquid    -   5, 6, 7, 8: support roller    -   10: lithographic printing plate precursor    -   12 a, 12 b: aluminum support    -   14: undercoat layer    -   16: image recording layer    -   20 a, 20 b: anodized film    -   22 a, 22 b: micropore    -   24: large-diameter pore    -   26: small-diameter pore    -   50: main electrolytic cell    -   51: AC power source    -   52: radial drum roller    -   53 a, 53 b: main pole    -   54: electrolytic solution supply port    -   55: electrolytic solution    -   56: auxiliary anode    -   60: auxiliary anode cell    -   111: rotary brush roll    -   113: transport roll    -   114: transport guide plate    -   115: spray pipe    -   116: pipe line    -   117: filter    -   118: plate feed stand    -   119: plate discharge stand    -   120: developer tank    -   122: dryer    -   130: lithographic printing plate precursor    -   410: anodization treatment device    -   412: power supply tank    -   414: electrolytic treatment tank    -   416: aluminum plate    -   418, 426: electrolytic solution    -   420: power supply electrode    -   422, 428: roller    -   424: nip roller    -   430: electrolytic electrode    -   432: cell wall    -   434: DC power source    -   ta: anodic reaction time    -   tc: cathodic reaction time    -   tp: time until current value reaches peak from zero    -   Ia: peak current on anode cycle side    -   Ic: peak current on cathode cycle side    -   W: aluminum plate

What is claimed is:
 1. A lithographic printing plate precursorcomprising: a hydrophilized aluminum support; and a water-soluble orwater-dispersible negative type image recording layer on the aluminumsupport, wherein an arithmetic average height Sa of a surface of anoutermost layer on a side opposite to a side where the image recordinglayer is provided is in a range of 0.3 μm to 20 μm, the image recordinglayer contains a polymer compound having a particle shape, and thepolymer compound having a particle shape has a hydrophobic main chainand both of (i) constitutional unit which contains a pendant-cyano groupdirectly bonded to the hydrophobic main chain and (ii) constitutionalunit which contains a pendant group having a hydrophilic polyalkyleneoxide segment.
 2. The lithographic printing plate precursor according toclaim 1, wherein the image recording layer contains an infraredabsorbing agent, a polymerization initiator, a polymerizable compound,and the polymer compound having a particle shape.
 3. The lithographicprinting plate precursor according to claim 1, wherein a Bekk smoothnessof the surface of the outermost layer on the side opposite to the sidewhere the image recording layer is provided is 1000 seconds or less. 4.The lithographic printing plate precursor according to claim 1, whereina resin layer which contains at least one kind of particles having anaverage particle diameter of 0.5 μm to 20 μm is provided as theoutermost layer on the side opposite to the side where the imagerecording layer is provided.
 5. The lithographic printing plateprecursor according to claim 4, wherein a film thickness of the resinlayer is in a range of 0.6 μm to 2 μm.
 6. The lithographic printingplate precursor according to claim 5 which satisfies Expression (A).0.2≤(the film thickness of the resin layer/the average particle diameterof the particles contained in the resin layer)≤0.5  Expression (A) 7.The lithographic printing plate precursor according to claim 4, whereina density of the particles is in a range of 500 pcs/m² to 500000 pcs/m².8. The lithographic printing plate precursor according to claim 4,wherein the resin layer contains a binder, and a difference insolubility parameter between the particles and the binder is 4 MPa^(1/2)or less.
 9. The lithographic printing plate precursor according to claim8, wherein the particles and the binder each contain at least oneselected from the group consisting of polyurethane, an acrylic resin,polystyrene, and polyethylene.
 10. The lithographic printing plateprecursor according to claim 4, wherein a 10% hardness of the particlesis 80 MPa or less.
 11. The lithographic printing plate precursoraccording to claim 1, wherein a plurality of protrusions are provided onthe surface of the outermost layer on the side opposite to the sidewhere the image recording layer is provided.
 12. The lithographicprinting plate precursor according to claim 1, wherein a resin layer isprovided as the outermost layer on the side opposite to the side wherethe image recording layer is provided, and a plurality of protrusionscontaining a polymer compound are provided on the resin layer.
 13. Thelithographic printing plate precursor according to claim 11, wherein anaverage height of the protrusions is in a range of 0.5 μm to 20 μm. 14.The lithographic printing plate precursor according to claim 11, whereina density of the protrusions is in a range of 500 pcs/m² to 500000pcs/m².
 15. The lithographic printing plate precursor according to claim1, wherein an arithmetic average height Sa of a surface of an outermostlayer on the side where the image recording layer is provided is smallerthan the arithmetic average height Sa of the surface of the outermostlayer on the side opposite to the side where the image recording layeris provided.
 16. The lithographic printing plate precursor according toclaim 1, wherein the aluminum support includes an aluminum plate and analuminum anodized film disposed on the aluminum plate, the anodized filmis positioned closer to the image recording layer side than to thealuminum plate, the anodized film has micropores extending in a depthdirection from the surface of the image recording layer side, and theaverage diameter of the micropores in the surface of the anodized filmis in a range of 7 nm to 150 nm.
 17. The lithographic printing plateprecursor according to claim 16, wherein the average diameter of themicropores in the surface of the anodized film is in a range of 10 nm to100 nm.
 18. The lithographic printing plate precursor according to claim16, wherein the micropores are formed of large-diameter pores extendingto a position at a depth of 10 nm to 1000 nm from the surface of theanodized film and small-diameter pores communicating with a bottom ofthe large-diameter pores and extending to a position at a depth of 20 nmto 2000 nm from a communication position, the average diameter of thelarge-diameter pores in the surface of the anodized film is in a rangeof 15 nm to 150 nm, and the average diameter of the small-diameter poresin the communication position is 13 nm or less.
 19. A lithographicprinting plate precursor laminate which is obtained by laminating aplurality of the lithographic printing plate precursors according toclaim 1, wherein an outermost layer on the side where the imagerecording layer is provided and the outermost layer on the side oppositeto the side where the image recording layer is provided are laminated bybeing directly brought into contact with each other.
 20. A method ofproducing the lithographic printing plate precursor according to claim1, comprising: a step of forming the image recording layer on thealuminum support after one or more days from an anodization treatmentperformed thereon.
 21. A lithographic printing method comprising: a stepof image-exposing the lithographic printing plate precursor according toclaim 1; a step of supplying at least any of printing ink or dampeningwater and removing an unexposed portion of an image recording layer on aprinting press to prepare a lithographic printing plate; and a step ofperforming printing using the obtained lithographic printing plate. 22.A lithographic printing method comprising: a step of image-exposing thelithographic printing plate precursor according to claim 1; adevelopment step of supplying a developer having a pH of 2 to 14 andremoving an unexposed portion; and a step of performing printing usingthe obtained lithographic printing plate.